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Crank no start when is cold

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Old Dec 22, 2023 | 11:41 AM
  #21  
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Originally Posted by LesMyer
OK - there is your problem - it's on that 12V power feed. Let me read schematics again.
we are at 68°. So I tested the cable for a second time while cranking, and this time, it started right up. Still I don't understand how can thus happen only when is cold.
 
Old Dec 22, 2023 | 11:57 AM
  #22  
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If the pink wire is hot with key on (engine not cranking), it should stay hot while engine is cranking. If not, then bad ignition switch. This should also be true at ECM 1 fuse in underhood fuse box. Let me add another test because it's easy - do the same at the ENG fuse.

It seems it will end up being ignition switch, but best to wait until it fails this last testing.

Current goes through the ignition switch during start and run positions to underhood fuse box and then splits. One part goes through ENG fuse in underhood fuse box and then evap canister purge solenoid, evap canister vent solenoid, MAF sensor, and cam position sensor. The other part goes through ECM 1 fuse in underhood fuse box - then to crank sensor, module, coil, ECM, & fuel injectors. I don't see any reason why any of these items whould drag the voltage down during cranking without blowing a fuse, but there is always a remote possibility of something off the wall.

I once had a customer's late 70's Olds Toronado because the intermittent wipers would take one swipe across the windshield every time the brake was depressed. Problem was a bad tail light bulb and a blown fuse. When the brakes were stepped on, voltage was conducted across the bulb by a broken turn filament lying across the tail lamp filament. Somehow the combo of the blown fuse and tail lamp bulb cause voltage to backfeed and trigger the intermittent wiper module to take a swipe. IIRC I had the logic on how this took place all laid out at the time, but as memorable as it was I just can't remember it anymore.

Another time I had a customer's Buick Firehawk (remember them) that would start and them immediately die. Turned out to be a bad voltage regulator in the alternator charging with such high voltage that the computer would freak out and shut things down to protect itself!

Nothing electrical on cars really surprises me anymore.
 

Last edited by LesMyer; Dec 22, 2023 at 12:46 PM.
Old Dec 22, 2023 | 12:46 PM
  #23  
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Please re-read post #22 - I added to it.
 
Old Dec 29, 2023 | 09:29 AM
  #24  
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Originally Posted by LesMyer
If the pink wire is hot with key on (engine not cranking), it should stay hot while engine is cranking. If not, then bad ignition switch. This should also be true at ECM 1 fuse in underhood fuse box. Let me add another test because it's easy - do the same at the ENG fuse.

It seems it will end up being ignition switch, but best to wait until it fails this last testing.

Current goes through the ignition switch during start and run positions to underhood fuse box and then splits. One part goes through ENG fuse in underhood fuse box and then evap canister purge solenoid, evap canister vent solenoid, MAF sensor, and cam position sensor. The other part goes through ECM 1 fuse in underhood fuse box - then to crank sensor, module, coil, ECM, & fuel injectors. I don't see any reason why any of these items whould drag the voltage down during cranking without blowing a fuse, but there is always a remote possibility of something off the wall.

I once had a customer's late 70's Olds Toronado because the intermittent wipers would take one swipe across the windshield every time the brake was depressed. Problem was a bad tail light bulb and a blown fuse. When the brakes were stepped on, voltage was conducted across the bulb by a broken turn filament lying across the tail lamp filament. Somehow the combo of the blown fuse and tail lamp bulb cause voltage to backfeed and trigger the intermittent wiper module to take a swipe. IIRC I had the logic on how this took place all laid out at the time, but as memorable as it was I just can't remember it anymore.

Another time I had a customer's Buick Firehawk (remember them) that would start and them immediately die. Turned out to be a bad voltage regulator in the alternator charging with such high voltage that the computer would freak out and shut things down to protect itself!

Nothing electrical on cars really surprises me anymore.
Sorry that i havent responde, I was busy on other stuff. I checked power in fuse ENG1 and there non when engine is cranking. But there is power from ignition switch when is open and cranking. Could the problem be at the fuse box or from the firewall to fusebox?
 
Old Dec 29, 2023 | 12:45 PM
  #25  
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Originally Posted by millosegura
Sorry that i havent responde, I was busy on other stuff. I checked power in fuse ENG1 and there non when engine is cranking. But there is power from ignition switch when is open and cranking. Could the problem be at the fuse box or from the firewall to fusebox?
Problem could be anywhere between the ignition switch and the underhood fuse box. Are you sure you are testing the correct cuicuit coming out of the ignition switch?
 
Old Dec 29, 2023 | 12:49 PM
  #26  
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Originally Posted by LesMyer
Problem could be anywhere between the ignition switch and the underhood fuse box. Are you sure you are testing the correct cuicuit coming out of the ignition switch?
I'm testing a pink cable with a light tester. There is power when I open the switch and there is power when is cranking. There one small pink wire and a big one. I'm testing the big one. I would the test tomorrow morning again to be sure
 
Old Dec 29, 2023 | 12:58 PM
  #27  
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Edited : sorry, info previously posted in this particular one was not correct. Ill try to get the correct pin assignment on the ignition switch connector.
 
Attached Files

Last edited by LesMyer; Dec 29, 2023 at 03:38 PM.
Old Dec 29, 2023 | 01:03 PM
  #28  
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Pink wire coming from ignition switch is the one you want to test. This the the 12V feed for both ECM1 and Eng1 fuses. See attachment in #27
 

Last edited by LesMyer; Dec 29, 2023 at 03:33 PM.
Old Dec 29, 2023 | 03:56 PM
  #29  
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Attachments show 1) location of C211 and 2) where pin C5 is in connector. This is the feed out of the ignition switch. You will need to arrow down to the C211 table in the first attachment to see the pin assignments.

You are nearing the end of the diagnosis.
 
Attached Files
File Type: pdf
1998Blazer C211 Pin C5.pdf (646.6 KB, 46 views)
File Type: pdf
1998Blazer C211 in Harness.pdf (83.8 KB, 46 views)

Last edited by LesMyer; Dec 29, 2023 at 04:03 PM.
Old Jan 4, 2024 | 08:41 AM
  #30  
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Originally Posted by LesMyer
Attachments show 1) location of C211 and 2) where pin C5 is in connector. This is the feed out of the ignition switch. You will need to arrow down to the C211 table in the first attachment to see the pin assignments.

You are nearing the end of the diagnosis.

It was the ignition switch. We are at 34° today, I replaced the ignition switch with one from the junk yard, just to see if it will start. I'll buy a new one. Thank you so much for your help


you can the discoloration in the right side of the terminals.
 



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