More found on this new to me 2000 GMC Jimmy (working on adding the spec in my user tag line).

1. The first issue I knew of beforehand, was the issue with the dome light not coming on nor the radio turning off when the drivers door is open which I started a dedicated thread to: (https://blazerforum.com/forum/lighti...or-open-98252/)
2. The second issue I knew of beforehand, the gauge cluster had issues. It had the stepper motor issue (which has since been corrected by someone who had a service). It also had issues with the odometer/trip display which I initially thought was perhaps a soldering issue. I have not gotten into the dash to verify just yet (wasn't a big concern, but now it may be) but now I am thinking it may be a bit more. It used to either be on and display fine or it would be just off. Now I am seeing anything from it having just a random number anywhere in the display pop up with nothing else or all options lit up at once or display correctly, or just the KM will be showing.
   
3. I have now also found that the fog lights are not working. I only had a quick minute to troubleshoot this but I was able to verify the under hood fuse is good, and tried another just in case. I swapped the horn relay for the fog light to test and still it does not work. The bulbs looked good, but did not directly test these with a battery. I did do a voltage test at the fuse and was only getting .24v.
4. The 4x4 selector seems to have intermittent issue with shifting while following the shift time/speed rules.
5. I cleaned the MAF and throttle body ( TB was left on the motor and yes I hand;t read before that I shouldn't have moved the butterfly manual. I drove the truck home (25 miles) with no engine light but did notice it would lurch coming to a stop and down shifting and would be almost like it had cruise control on at lower speeds. Started it this morning and instantly got the engine light, pulled the code to be P0507. I have been driving around all day seeing if it will relearn and clear on its own with no luck. I just did the detach battery and 3 brake pedal presses oddly enough has worked to clear but I haven't yet tested the idle or driven yet.
6. Dome light override doesn't work. I mention this because at this moment I am unsure if this is tied to my driver door ajar (issue 1) or if it is supposed to work for passenger doors because if it is, that does not work either.
7. Perhaps the biggest issue I am having is I cannot get the secondary air smog system to complete its test in the scan tool so i can get it smogged. I have had many cold starts, GM drive cycles, driven 2 tanks of gas and it still remains. Not sure if this is on its own per perhaps part of all these issues I am starting to think is a BCM issue.
8. The best I can tell, from the intermittent trip counter working. I am getting about 12-13mpg in this thing. I knew it would be lower, even figured getting that lower end EPA estimate of 16mpg even on the freeway, but this is a bit crazy, might as well have gotten a suburban. New air filter in.. and I have new wires and plugs to put in, and and oil change to do but hopes are low. side note could anyone point me to a thread on tips on plug changes? I saw one before regard may be needing to remove a tire to get to a tough plug but can't find it now.

So as I mentioned in #6 I am starting to think with all these electrical issues maybe there is a BCM problem rather than individual electrical issues. Some things I have done just to cover bases that are not mention already in the #1 thread.. I have put all new fuses into the interior drivers fuse panel, it has a brand new battery.
Open to both individual issue suggestions or anything to lean to maybe a signal issue causing them all like BCM.
I am also wondering where is best to get a factory service manual for this truck so I have the wiring diagrams and also if anyone can give me some locations of body grounds to check in the meantime.
Thanks in advance for taking the time to read this and any help.

 

Couple updates:
Pertaining to the MAF, TB, and IAC.I drove another 50 miles today and eventually the P0507 code popped back up and all the while I had the higher idle until i stopped for a bit. I pulled off the IAC and cleaned it and the bypass area of the TB off. Little bit of crap but nothing too alarming to me. Codes were cleared again with the battery disconnected for the work, drove home and still had the idle issue but no check engine light..yet.
Regarding #7 and the smog, Since resetting the codes I have to start back over on getting all the smog items to complete. Getting back through the ones that worked liked the egr and o2 but the secondary air isnt completing still. I have been trying the GM Drive cycle int he morning, as best I can with lights and traffic, and I am now starting the truck at night after sitting all afternoon to get another cold start in.

For the overall electrical, I have another shot of a different dash display. One of the random placement numbers that dont change while on and do not seem to be part of mileage/trips etc.

Again, help on any topic would be greatly appreciated.

 

I've been investigating how to create an override circuit for the daytime-running-lights/auto-headlights and in the process found that very many of these things (definitely all of the lighting) are run through the body-control module (BCM). So I think your suspicions could be correct. Have you tried disconnecting the electrical connectors for the BCM and underhood fuse block? There is also the Body Relay Block (BRB) that has a bunch of relays on it.

Regarding the gauges, when one of my stepper motors went bad I just pulled a new gauge cluster from another Blazer. The odometer was off but otherwise it worked.

I've attached scans of some of the schematics I've created from my hard-copy service manual I purchased off of eBay. Perhaps these will help with #1, #3, or #6.

 

Awesome, thank you very much for the schematics! I haven't made my way to the BCM as I was slowly uncovering these other issues as I drive it and or troubleshoot others. I will have to find it and the other items and play with those as well to see what I can get.
I bought new Throttle position sensor, new IAC and a new TB gasket. I took off the TB and ran it few a few cleaning cycles in my sonic cleaner and put all the new parts back on and am still getting the high idle code popping back up after clearing the codes and driving. To make it worse, after all these parts and getting the same code I then got a code, for an O2 sensor out of spec. I forgot to take a screen shot of the code number before clearing and trying the drive cycle again but I have the detailed test results below. Not sure how changing these new parts would then trigger O2 issues, but sounds like I fix something the next weakest thing goes haha. I may have to start a smog specific thread I suppose but if anyone is familiar with $06 codes let me know what you think.
Test report:
------------------
TID:$02 CID:$04
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$10
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$11
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$12
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$20
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$21
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$26
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$30
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$31
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$36
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$40
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$46
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$06 CID:$35
- Lean to Rich sensor switch time(calculated)
Max: 74
Test result value: 33
PASS
----
TID:$06 CID:$47
- Lean to Rich sensor switch time(calculated)
Max: 210
Test result value: 72
PASS
----
TID:$06 CID:$55
- Lean to Rich sensor switch time(calculated)
Max: 73
Test result value: 30
PASS
----
TID:$07 CID:$0c
- Minimum sensor Voltage for test cycle(calculated)
Max: 0
Test result value: 56,320
FAIL
----
TID:$07 CID:$0d
- Minimum sensor Voltage for test cycle(calculated)
Max: 155
Test result value: 56,320
FAIL
----


End of report.

 

Just to throw it out there: On the 92 Blazer I used to have I kept getting an O2 sensor error so I dutifully replaced it only to have the error eventually come back. What turned out to be the problem was that my fuel injection spider was leaking, dumping raw fuel into the engine causing an over-rich condition that fouled the O2 sensor. I mention this as a reminder, if you have not done so already, to keep in mind that sometimes the symptoms are indicative of a larger fault rather the thing reporting the fault.

 

Funny you should mention exactly that. I ran across a post regarding the SCPI to MPFI upgrade on a silverado and made me want see if I could do it to the jimmy. But whether I can or cannot it made me wonder if it was the fuel efficiency issue on this truck even with it's lower miles. I was waiting to get back to my computer to post these pictures I took while the TB was off and noticed the distinctively clean side.
If that is the case, I still wonder why it would clear all tests (except the secondary air) until cleaned the TB..then throw the high idle code, then the O2 code after I get the TPS and IAC replaced. I suppose the IAC could have been stuck more open and compensating a bit for the over injection of fuel witht he extra air then drop the airflow with the working IAC.... but I digress: I assume at least to 2 clean ones I can see are cleaned by the gas or stuck or leaking.. Is it possible to do a MPFI swap on this 2000 jimmy?

 

posted the question too fast is all this information correct and what I am looking for? (https://blazerforum.com/forum/2nd-ge...n-92537/page2/)
Thank you

 

This webpage helped me understand what fuel injection systems were used for each year. Vortec CSFI to MPFI conversion

The short answer to your question is Yes. The new style injectors were not used on new vehicles until 2002 but they can be installed on vehicles made from 96-01.

Those clean areas with no carbon build-up are a good clue that you have a fuel leak.

I replaced my injectors when I had the top of my motor apart to replace the lower intake manifold (LIM) gaskets. I was glad I did as I could see where they were starting to fail.

 

Thanks for the confirmation. I am going to do the intake gaskets while I am in there with the updated fel pro set with the metal mesh as that blazerforum thread i linked mentioned.

II am now wondering if this is the same injector set as this kit. I am getting this and would assume save the bucks and not get duplicate gaskets if it is the same.

 

Going by the pictures, those look like the correct style for the upgraded injectors and the correct upgraded LIM gaskets. The gasket set is all you will need. You might get a couple extra gaskets with the fuel injection spider but I wouldn't worry about it.