I need the schematic wiring diagram and VCM Pinout to troubleshoot failed IAC failure. Please help.

 

Here ya go

George

 

Thanks George, and I really appreciate your response to my request. I was able to locate a 1995 Systems Wiring Diagram. This blazer belongs to my elderly Aunt who inherited from a close friend who purchased new in '95. So the blazer has sentimental value in it that she feels compel to maintain in perfect running condition. My initial test drive determined the vehicle has rough idling, acceleration, stalling, and shut-off. It also backfired so loud, someone removed the catalytic converter and muffler was blown. After it shut down it wouldn't start again until after it cooled (normally 2 hours or more) and run for another 10 minutes and shut down again. The service engine light is on and I immediately tried to pull codes. To my surprise, this vehicle (1995) has an OBDII data port connector but operates on the OBDI protocol. Not being able to use the paper clip jumping process or a GM code reader, I connected my Autel scanner but wasn't able to get it to communicate with the onboard computer. I went to manual checks and started with fuel pressure. The fuel pressure was good but significant bleed down was recognized. I pulled the upper intake plenum and energized the fuel pump and saw leaking from fuel regulator. I changed the regulator and that corrected the leak and fuel pressure. Not being able to pull any codes, I started checking sensor responses by disconnecting during idling and the IAC was unresponsive. The vehicle being 30 years old, and no evidence of major sensor replacements, I changed the MAF, TPS, crank & cam sensors. There was no change in running status and still no response from IAC. Changing my focus to the VCM, it showed evidence it had been tampered with. My uncle revealed he replaced the original computer with one from a local junkyard. He said he replaced it because the vehicle was using a lot of fuel. This was nearly 4 years ago and said it ran find until current issues. He sent me the original computer and after changing it, the vehicle stop shutting down, but the idling, and stalling and backfiring still were there. I ordered a computer from Flagship I and upon installing it, the vehicle ran & accelerated great. The problem was the start-up rpm was 1200 and instead of dropping down to normal rpms, it steadily increased until I shut it down at 2500 rpm. It was like it was in a runaway status. I sent back to Flagship and waiting on another unit. I did determine the 95 blazer was an transition year and it has an OBD1.5 system. I have since ordered an ALDL computer USB interface to connect to my laptop but will need to download a Scanapp. Scan 9495, made for the LT1, to my beliefs will not work. My other option is the GM Tech2 Monitor. If there are any other suggestions, I would greatly appreciate it. By the way, I will be changing the O2 sensor today. Thanks to this forum.

 

Scanning ODB1.5 is a PITA. That said, some older Actron models can do this. I think that the CP9145 was one of them. You can find them used on ebay. Try to confirm that I have then correct model number.

George

 

Ok thanks Mr GeorgeLG. I will check and let the forum know.