ECM Diagnosis ?
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New Member
Joined: Oct 2022
Posts: 6
ECM Diagnosis ?
I just joined the Forum and find it very informative.
I have run into a problem and need help at this point. A little background. I was in a major accident and have spent most of the last 3 plus years in and out of the hospital and rehab. As a result the trusty 2001 Blazer LS has set idle for almost 4 years now. I decided to get it going again as it is one of the best vehicles I have ever owned.
To start, the battery was flat even though I used a battery maintainer (1.2 amps). I popped the lid on the battery and it looked completely dry. I filled it with distilled water and put it on the charger. The battery was a brand new 700 amp Everstart installed just before the accident. I thought it might have a chance. I was surprised that it started taking charge at 15 amps. After 4 hours of charging it was at 13.3 volts and held it overnight. I put the battery back ìn the Blazer and tried it. It would only click the solenoid and dropped to 9 volts. Hooked up the charger again and it barely turned the motor and quit. Frustrated, I hooked up the giant diesel tractor battery along with the charger. The Blazer started and ran about a minute, then died. Went and bought a new 700 battery and installed it. Blazer started and ran about 15 seconds and died. Same results on repeated attempts.
I checked all the fuses in both terminal boxes and all were good. You can hear the fuel pump running when you turn on key. I did note that the gouges look like they are working, but there are no indicator lights on the dash and no power to the radio/security system. The parking lights and taillights are on and cannot be turned off. Had to pull the fuse. The key fob will not work and will not reprogram. The lift glass latch will not work from the fob or dash button. No power to any of the interior lights.
I talked to a neighbor who also has a 2001 Blazer. He said the most likely problem is a bad ECM based on the symptoms I described. He thinks that the long time sitting allowed corrosion to the ECM board which then shorted out when I tried to start it. He said a new ECM would cure the ailments, but I would have to reprogram the security system.
Am I on the right track before I purchase a new ECM?
I have run into a problem and need help at this point. A little background. I was in a major accident and have spent most of the last 3 plus years in and out of the hospital and rehab. As a result the trusty 2001 Blazer LS has set idle for almost 4 years now. I decided to get it going again as it is one of the best vehicles I have ever owned.
To start, the battery was flat even though I used a battery maintainer (1.2 amps). I popped the lid on the battery and it looked completely dry. I filled it with distilled water and put it on the charger. The battery was a brand new 700 amp Everstart installed just before the accident. I thought it might have a chance. I was surprised that it started taking charge at 15 amps. After 4 hours of charging it was at 13.3 volts and held it overnight. I put the battery back ìn the Blazer and tried it. It would only click the solenoid and dropped to 9 volts. Hooked up the charger again and it barely turned the motor and quit. Frustrated, I hooked up the giant diesel tractor battery along with the charger. The Blazer started and ran about a minute, then died. Went and bought a new 700 battery and installed it. Blazer started and ran about 15 seconds and died. Same results on repeated attempts.
I checked all the fuses in both terminal boxes and all were good. You can hear the fuel pump running when you turn on key. I did note that the gouges look like they are working, but there are no indicator lights on the dash and no power to the radio/security system. The parking lights and taillights are on and cannot be turned off. Had to pull the fuse. The key fob will not work and will not reprogram. The lift glass latch will not work from the fob or dash button. No power to any of the interior lights.
I talked to a neighbor who also has a 2001 Blazer. He said the most likely problem is a bad ECM based on the symptoms I described. He thinks that the long time sitting allowed corrosion to the ECM board which then shorted out when I tried to start it. He said a new ECM would cure the ailments, but I would have to reprogram the security system.
Am I on the right track before I purchase a new ECM?
BF Veteran
Joined: Jan 2007
Posts: 4,625
From: Florida
Some of these problems do not involve the PCM and/or involve the BCM, not the PCM. . Could you have a bad PCM, sure but I am not convinced.
Does it starts every time and then quit every time after a few seconds? What’s your system voltage while it running at the ICM or coil pink wire?
Does the security light ever come on or flash?
Are there any codes?
Did any of these problems occur before the long layup?
George
Does it starts every time and then quit every time after a few seconds? What’s your system voltage while it running at the ICM or coil pink wire?
Does the security light ever come on or flash?
Are there any codes?
Did any of these problems occur before the long layup?
George
Thread Starter
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New Member
Joined: Oct 2022
Posts: 6
I just joined the Forum and find it very informative.
I have run into a problem and need help at this point. A little background. I was in a major accident and have spent most of the last 3 plus years in and out of the hospital and rehab. As a result the trusty 2001 Blazer LS has set idle for almost 4 years now. I decided to get it going again as it is one of the best vehicles I have ever owned.
To start, the battery was flat even though I used a battery maintainer (1.2 amps). I popped the lid on the battery and it looked completely dry. I filled it with distilled water and put it on the charger. The battery was a brand new 700 amp Everstart installed just before the accident. I thought it might have a chance. I was surprised that it started taking charge at 15 amps. After 4 hours of charging it was at 13.3 volts and held it overnight. I put the battery back ìn the Blazer and tried it. It would only click the solenoid and dropped to 9 volts. Hooked up the charger again and it barely turned the motor and quit. Frustrated, I hooked up the giant diesel tractor battery along with the charger. The Blazer started and ran about a minute, then died. Went and bought a new 700 battery and installed it. Blazer started and ran about 15 seconds and died. Same results on repeated attempts.
I checked all the fuses in both terminal boxes and all were good. You can hear the fuel pump running when you turn on key. I did note that the gouges look like they are working, but there are no indicator lights on the dash and no power to the radio/security system. The parking lights and taillights are on and cannot be turned off. Had to pull the fuse. The key fob will not work and will not reprogram. The lift glass latch will not work from the fob or dash button. No power to any of the interior lights.
I talked to a neighbor who also has a 2001 Blazer. He said the most likely problem is a bad ECM based on the symptoms I described. He thinks that the long time sitting allowed corrosion to the ECM board which then shorted out when I tried to start it. He said a new ECM would cure the ailments, but I would have to reprogram the security system.
Am I on the right track before I purchase a new ECM?
I have run into a problem and need help at this point. A little background. I was in a major accident and have spent most of the last 3 plus years in and out of the hospital and rehab. As a result the trusty 2001 Blazer LS has set idle for almost 4 years now. I decided to get it going again as it is one of the best vehicles I have ever owned.
To start, the battery was flat even though I used a battery maintainer (1.2 amps). I popped the lid on the battery and it looked completely dry. I filled it with distilled water and put it on the charger. The battery was a brand new 700 amp Everstart installed just before the accident. I thought it might have a chance. I was surprised that it started taking charge at 15 amps. After 4 hours of charging it was at 13.3 volts and held it overnight. I put the battery back ìn the Blazer and tried it. It would only click the solenoid and dropped to 9 volts. Hooked up the charger again and it barely turned the motor and quit. Frustrated, I hooked up the giant diesel tractor battery along with the charger. The Blazer started and ran about a minute, then died. Went and bought a new 700 battery and installed it. Blazer started and ran about 15 seconds and died. Same results on repeated attempts.
I checked all the fuses in both terminal boxes and all were good. You can hear the fuel pump running when you turn on key. I did note that the gouges look like they are working, but there are no indicator lights on the dash and no power to the radio/security system. The parking lights and taillights are on and cannot be turned off. Had to pull the fuse. The key fob will not work and will not reprogram. The lift glass latch will not work from the fob or dash button. No power to any of the interior lights.
I talked to a neighbor who also has a 2001 Blazer. He said the most likely problem is a bad ECM based on the symptoms I described. He thinks that the long time sitting allowed corrosion to the ECM board which then shorted out when I tried to start it. He said a new ECM would cure the ailments, but I would have to reprogram the security system.
Am I on the right track before I purchase a new ECM?
Some of these problems do not involve the PCM and/or involve the BCM, not the PCM. . Could you have a bad PCM, sure but I am not convinced.
Does it starts every time and then quit every time after a few seconds? What’s your system voltage while it running at the ICM or coil pink wire?
Does the security light ever come on or flash?
Are there any codes?
Did any of these problems occur before the long layup?
George
Does it starts every time and then quit every time after a few seconds? What’s your system voltage while it running at the ICM or coil pink wire?
Does the security light ever come on or flash?
Are there any codes?
Did any of these problems occur before the long layup?
George
It starts every time (about 20 tries), runs 10 to 15 seconds, then dies.
I don't have the voltage info at the coil. I did install a new coil about 6 months before the long idle time thinking it would help the hard starting during wet weather. The new coil did not help with that issue. I am pretty much crippled now and can't physically get out of the Blazer before it dies. I have no one to assist.
The security light never comes on, nor do any of the other lights above the gouges. No interior lights or power to radio. All this was functioning normally before the long sitting time.
I don't have a code reader, but it has shown a check engine light for many years. That code was for the air pump. I replaced the air pump twice during the first years of ownership, but both only lasted 6 months. At $600 a pop, it was not replaced again. It ran fine without the air pump.
None of these problems existed before the long idle time.
I am confused about all the electrical problems that were not present before, and no fuses blown. The only real problem that has surfaced so far is the vacuum hose to the 4x4 dash pot was pretty rotten and broke every place it was crimped to check for leaks. I bought replacement hose but it is not installed as it is pouring the rain right now.
My only other thought was a short in the wiring harness, but that doesn't really fly as there should have been a blown fuse somewhere.
BF Veteran
Joined: Jan 2007
Posts: 4,625
From: Florida
When it starts but then dies, will it start right back up again or does it need to rest before it will start?
Does it always crank?
There can be wiring harness problems that do no blow fuses, we find them here all the time.
What we need to find out is why does it stop running:
Fuel pressure
Ignition
Mechanical problems
etc
I asked about the security light because if the security system has failed like the passlock module the truck will start and run and then die as the fuel injectors are disabled.
George
Does it always crank?
There can be wiring harness problems that do no blow fuses, we find them here all the time.
What we need to find out is why does it stop running:
Fuel pressure
Ignition
Mechanical problems
etc
I asked about the security light because if the security system has failed like the passlock module the truck will start and run and then die as the fuel injectors are disabled.
George
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New Member
Joined: Oct 2022
Posts: 6
ECM Diagnosis?
Per your questions.
Yes. It starts every time I have tried. No rest period is needed.
Yes. It has cranked every time. I have tried about 30 times and it has cranked and started every time.
I once had a Bronco between a K5 Blazer and the current S10 Blazer. It developed some strange electrical problems. I can't remember exactly all that it was doing ,30 plus years ago, but a good mechanic traced the problem back to a fusible link in the wiring that was bad. I do remember that there were no blown fuses there also. I never would have found it on my own. I didn't even know there was a fusible link in the system.
Some more test results.
1. The light control panel on the dash doesn't work at all for any of the functions. I still have the parking lights fuse pulled to prevent running down the battery. Forgot to. Plug it back in before testing.
2. No dash back lighting. The only lights working on the. Dash panel are the check engine light when the switch. Is turned to run and the high beam indicator stays lit. All the time. No interior lights. No radio. No security. System. It acts like the entire dash is dead except for. the check engine light and the high beam indicator. my very limited experience with vehicles electrical. systems, it acts like a bad ground in the system. I. have had strange lighting problems with the taillights caused by a bad ground and back feeding thru. Another light with a good ground. No blown fuses. With that experience either. Sounds kind of like I'm. Chasing the wrong system. Hot side versus ground. Side. You can blow fuses with a short to ground, but. Not with a bad ground. Does that make any sense, or. Am Chasing a cold trail?
Yes. It starts every time I have tried. No rest period is needed.
Yes. It has cranked every time. I have tried about 30 times and it has cranked and started every time.
I once had a Bronco between a K5 Blazer and the current S10 Blazer. It developed some strange electrical problems. I can't remember exactly all that it was doing ,30 plus years ago, but a good mechanic traced the problem back to a fusible link in the wiring that was bad. I do remember that there were no blown fuses there also. I never would have found it on my own. I didn't even know there was a fusible link in the system.
Some more test results.
1. The light control panel on the dash doesn't work at all for any of the functions. I still have the parking lights fuse pulled to prevent running down the battery. Forgot to. Plug it back in before testing.
2. No dash back lighting. The only lights working on the. Dash panel are the check engine light when the switch. Is turned to run and the high beam indicator stays lit. All the time. No interior lights. No radio. No security. System. It acts like the entire dash is dead except for. the check engine light and the high beam indicator. my very limited experience with vehicles electrical. systems, it acts like a bad ground in the system. I. have had strange lighting problems with the taillights caused by a bad ground and back feeding thru. Another light with a good ground. No blown fuses. With that experience either. Sounds kind of like I'm. Chasing the wrong system. Hot side versus ground. Side. You can blow fuses with a short to ground, but. Not with a bad ground. Does that make any sense, or. Am Chasing a cold trail?
BF Veteran
Joined: Jan 2007
Posts: 4,625
From: Florida
Some but not all of these problems involve the BCM (body control module) so if any computer module is suspect its that one but more testing is needed. There are also various fuses, switches, wiring and relays. Bad grounds and back feeding are a possibility on some of these but thats not the highest likely hood. A ground most likely did not go bad sitting. Blown fuses, stuck relays, corroded wires, damaged modules are more likely especially with bad batteries and jump starting. Load dumps can damage a lot of components.
You can have a wiring harness short that does not blow fuses like say a short to another circuits power causing the first circuit to be energized all the time.
The keyfob needs the BCM and the wireless receiver
The interior lights need the BCM and various relays and switches
The liftglass uses the BCM except for any rear liftglass button or key switch
Older trucks used more fusible links, your truck only has one between the battery and alternator
1) Have you checked all of the fuses in both fuse panels?
2) Can you use a digital volt meter and be able to take some measurements? Can you crawl around under the dash?
3) When you say the radio is dead do you mean the backlight or the whole radio does not turn on? The backlight bulb does not use the BCM.
4) On the parking lamps always being on, pull the park lamp relay and see if they go out (fuse back in)
5) The IPC panel backlights dont go through the BCM, they get powered from the headlamp switch thumbwheel. If you manually turn on the headlights, does the illumination bulb in that headlamp switch light up? How about the other dash bulbs like the 4x4 indicator? Is that interior light thumbwheel all the way up?
6) If you have a rear liftglass button or key switch on the back "door" does that work to unlock the glass if the drivers door is unlocked?
7) If your engine cuts out because of a lack of fuel pressure that is the pump, spider or regulator. Can you do the leakdown part of the fuel pressure test at the schrader? If it dies because you lose the fuel injector pulses then that involves the ignition switch assembly and again the BCM
I know you have limitations and I am asking a lot of questions. You have a lot going on with this truck and I am trying to prevent an unnecessary expensive parts cannon discharge by proper analysis. There is no single component to explain this entire list but one of the possibilities as I said is the BCM not the engine computer (PCM)..
A complicated problem like this is tough remote control but I will help you the best I can and stick with you as long as you need me.
George
You can have a wiring harness short that does not blow fuses like say a short to another circuits power causing the first circuit to be energized all the time.
The keyfob needs the BCM and the wireless receiver
The interior lights need the BCM and various relays and switches
The liftglass uses the BCM except for any rear liftglass button or key switch
Older trucks used more fusible links, your truck only has one between the battery and alternator
1) Have you checked all of the fuses in both fuse panels?
2) Can you use a digital volt meter and be able to take some measurements? Can you crawl around under the dash?
3) When you say the radio is dead do you mean the backlight or the whole radio does not turn on? The backlight bulb does not use the BCM.
4) On the parking lamps always being on, pull the park lamp relay and see if they go out (fuse back in)
5) The IPC panel backlights dont go through the BCM, they get powered from the headlamp switch thumbwheel. If you manually turn on the headlights, does the illumination bulb in that headlamp switch light up? How about the other dash bulbs like the 4x4 indicator? Is that interior light thumbwheel all the way up?
6) If you have a rear liftglass button or key switch on the back "door" does that work to unlock the glass if the drivers door is unlocked?
7) If your engine cuts out because of a lack of fuel pressure that is the pump, spider or regulator. Can you do the leakdown part of the fuel pressure test at the schrader? If it dies because you lose the fuel injector pulses then that involves the ignition switch assembly and again the BCM
I know you have limitations and I am asking a lot of questions. You have a lot going on with this truck and I am trying to prevent an unnecessary expensive parts cannon discharge by proper analysis. There is no single component to explain this entire list but one of the possibilities as I said is the BCM not the engine computer (PCM)..
A complicated problem like this is tough remote control but I will help you the best I can and stick with you as long as you need me.
George
Last edited by GeorgeLG; Oct 17, 2022 at 11:00 PM.
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New Member
Joined: Oct 2022
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Response
George. Thank you for all the help. You are correct that I have limited mobility. I broke a hip in the pelvic bone past the socket joint. The surgeon botched the surgery, then retired. The metal inserts are bending resulting in very limited and much pain. I also had a very large hematoma in the right leg. They cut me from groin toward the knee 10 inches long and clear to the bone. The result of that was 8 more surgeries to drain a combination of Staff and MERSA infections. I'm a walking billboard for a broken medical system. I am scheduled for a foot amputation on 10/28 that was the result of a toe amputation several years ago. Yes. I am really messed up physically.
It's snowing outside right now. I will start checking the latest list of items when the weather clears a bit.
It's snowing outside right now. I will start checking the latest list of items when the weather clears a bit.
BF Veteran
Joined: Jan 2007
Posts: 4,625
From: Florida
You hang in there brother, I am sorry for your suffering. Sometimes life’s not fair by a good bit but we get up in the morning and deal with the hand we are dealt the very best we can and get another good day in the books. Snowing in October, where are you located?
I would like to help you get your truck fixed. I am going to spend some time in the GM service manual today regarding these issues, especially the BCM. I will also try to limit the testing to get to the bottom of this to help you out.
George
I would like to help you get your truck fixed. I am going to spend some time in the GM service manual today regarding these issues, especially the BCM. I will also try to limit the testing to get to the bottom of this to help you out.
George
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New Member
Joined: Oct 2022
Posts: 6
George. Thank you for all the help so far. I was able to get a few answers to the latest questions.
1. I have checked all the fuses in both panels. First with a meter, second with a test light, and third by pulling each fuse and physically checking each fuse. The door lock fuse was the only bad one I found. I replaced it and all 4 cycle on/off. 3 of the doors the lock works normally. The driver door cycles, but the actual function does not. It will lock but not unlock.
2. I can use a digital volt meter, but crawling under the dash is very difficult and painful. The right hip only works in a straight line motion. It is very painful to twist and turn. I have enlisted help from a neighbor, but he is not available until after the scheduled amputation of the left foot. Time is running short and further testing will have to wait until I'm back on my feet. I hate the added complication but that is out of my control.
3. The whole radio will not turn on. The backlight does not work on the radio or dash no matter the dimmer wheel position. Also, the auto, parking lights and headlights do not work from the switch panel.
4. Pulling the park lamp relay with the fuse back in doesn't shut off the parking lights.
5. No lights work from the switch panel and the thumb wheel position doesn't have any effect.
6. Neither the button on the dash or the key fob will unlock the back hatch.
7. I have a pressure gage I can modify the connection. What is a Schrader and where is it located?
Believe it or not I'm in central KY. Richmond to be specific. We have crazy weather here. Unusual cold spell now with flurries at night. Supposed to be back in 60's late next week.
1. I have checked all the fuses in both panels. First with a meter, second with a test light, and third by pulling each fuse and physically checking each fuse. The door lock fuse was the only bad one I found. I replaced it and all 4 cycle on/off. 3 of the doors the lock works normally. The driver door cycles, but the actual function does not. It will lock but not unlock.
2. I can use a digital volt meter, but crawling under the dash is very difficult and painful. The right hip only works in a straight line motion. It is very painful to twist and turn. I have enlisted help from a neighbor, but he is not available until after the scheduled amputation of the left foot. Time is running short and further testing will have to wait until I'm back on my feet. I hate the added complication but that is out of my control.
3. The whole radio will not turn on. The backlight does not work on the radio or dash no matter the dimmer wheel position. Also, the auto, parking lights and headlights do not work from the switch panel.
4. Pulling the park lamp relay with the fuse back in doesn't shut off the parking lights.
5. No lights work from the switch panel and the thumb wheel position doesn't have any effect.
6. Neither the button on the dash or the key fob will unlock the back hatch.
7. I have a pressure gage I can modify the connection. What is a Schrader and where is it located?
Believe it or not I'm in central KY. Richmond to be specific. We have crazy weather here. Unusual cold spell now with flurries at night. Supposed to be back in 60's late next week.
Last edited by Willy53; Oct 21, 2022 at 05:52 AM.
BF Veteran
Joined: Jan 2007
Posts: 4,625
From: Florida
Hey *****, thanks for the information. I’m on the road out of town today so I won’t get a chance to look at this until the weekend but I can already see from a couple of your answers that there are problems that do not involve any of your computers ECM or BCM. These answers will help me work with you to figure out what happened to your truck but I want to take the time to come up with a plan that minimizes the stress on you personally and gets us to the answer.
George
George