Bad Computer?

[jojorios]

Hopefully someone can point me in right direction on my issue.

I have a 96 Blazer LS with about 92000 miles, and have been having nothing but problems lately. The car pretty much still has all it's original parts. Right now my car is idling at 1.5 RPM. I took it to the mechanic and changed the IAC and the car remained at that idle. I cleaned up the throttle body and checked the voltage on the TPS and they where normal. The mechanic mentioned that the next thing to "replace" was the computer that controls the idle. One thing that did change was that now my service engine light was coming on giving code P0507 (Idle Control System RPM Higher Than Expected) which it wasn't before. Are there any other things I should check before going ahead with his next step?

Now my next problem which I don't know if it may be related. For the past few months, when I would start my car, it would randomly start with the battery light on. The voltage was at about 10-12. After driving the car for about 15 minutes it would go away and operate as normal. I took it to my friend who works at Autozone and he ran a test on the Battery and alternator and they passed perfectly. Tonight I got the battery light again, but this time it didn't go away. The voltage started to slowly go down until it hit 9 and it died on me. My fiancee came to give me a boost and the boost worked for about 1/2 a mile until it died again. Took 5 boosts to get me home. Luckily i was about 2 miles away. Is it possible this is all related to the computer? Or do I just have a whole mess of problems to get ready to deal with?

Are there ways of testing the computer without going to a dealership or should I just bite the bullet and take it there so they can run a full diagnostics on it?

Thank you all in advance.

[blazes9395]

These two problems could very well be connected. For the PCM to operate properly, it needs proper voltage. If the truck is running only on the battery and dies out, its not running on its proper voltage and the PCM, along with other electrical things, will do funny things. You need to get your charging system working properly first. Also, you could have a bad alternator regualtor, or bad connections. Check the connections to the alternator and go from there. The battery light indicates that the alternator is not charging, you need to find that probelm first and go from there.

[old_master]

The ECM is a very substantial part and rarely "goes bad". The most common reason they "go bad" is the technician doesn't know how to troubleshoot correctly and he's guessing. Don't let him replace anything until you post the DTC's here, we can help you. Blazes9395 is 100% correct, repair the charging system first. Then post the DTC's, ...if there are any

[jojorios]

Well I took the alternator and batterty to Autozone and i ran the test on them and they both failed. Said screw it and bought new ones. Installed them today and car is running again, unforunately it is still reving at 1.5 at idle. Any suggestions on what to check on next? Also to check the computer, do mechanics usually have the equipment to test or is it more of a thing where I have to take it to the dealership?

[Sinful7]

Originally Posted by old_master

The ECM is a very substantial part and rarely "goes bad". The most common reason they "go bad" is the technician doesn't know how to troubleshoot correctly and he's guessing. Don't let him replace anything until you post the DTC's here, we can help you. Blazes9395 is 100% correct, repair the charging system first. Then post the DTC's, ...if there are any

If anyone has a FSM for 95, you could test the ECM via the listed procedure. I had to replace the ECM on my '92 at 167,xxx.

[jojorios]

Well after all this I put in a new VCM and my seems to now be working as normal. No more loss of power, no more high rev. Hopefully this will be the last of my issues in a long time. If the car seems to be ok for another 3 or 4 months maybe i'll buy it some new shocks.

Thank you all for all your help!