1986 Chevy S-10 Blazer Burning ECM - short?

Tiny
REALAMERICAN
  • MEMBER
  • 1986 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 230,000 MILES
I own a 1986 Chevy S-10 Blazer. I keep burning up a component inside my ECM. My truck runs fine until the ECM burns up, usually after a day after installation. Then the truck misses throughout the speed range, and backfires occasionally. After the ECM burns up, I check my timing and the timing is way off. Resetting the timing fixes the backfire problem but it continues to miss random cylinders. I have new spark plugs and wires and a relatively new distributer. I have uploaded a picture to show which chip is burning up, in hopes that somebody has the schematics to determine what this chip controls. Something has got to be shorting out somewhere.


http://www.2carpros.com/forum/automotive_pictures/136989_DSC00508_copy_small_1.jpg


If you need a larger, more detailed picture, I have them available to email. If you need any other info, I'll give it to you. Im at the end of my rope here. Any ideas?
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Tuesday, January 1st, 2008 AT 11:26 AM

12 Replies

Tiny
FISHERMAN
  • EXPERT
Hello !

Well It`s going to be hard to find an schematic for the ECM but I have a suggestion:

follow the circuit board lines that leads to the chip and see the color codes on the connector, that way I can get you an a wiring schematic and with the color of the wires we will know what sensor/actuator or device its feeding.

What do you think?

Let me know!

Good luck!

BTW Thanks a Lot for your donation!

I`ll be in contact!
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Wednesday, January 2nd, 2008 AT 10:48 PM
Tiny
REALAMERICAN
  • MEMBER
Ok, I looked at the bottom of the board. Most of the leads go to other chips, all of which look fine. There are four leads that run to the electrical connectors. I have uploaded pictures of my trace and have labeled everything.


https://www.2carpros.com/forum/automotive_pictures/136989_DSC00511_copy_1.jpg



https://www.2carpros.com/forum/automotive_pictures/136989_DSC00515_copy_1.jpg



https://www.2carpros.com/forum/automotive_pictures/136989_DSC00516_copy_1.jpg



Wire 1 leads to Connection A2 which runs into a brown wire
Wire 2 leads to Connection A3 which runs into an empty socket
Wire 3 leads to Connection C1 which runs into a black wire with a purple stripe
Wire 4 leads to Connection C2 which runs into an empty socket.
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Thursday, January 3rd, 2008 AT 11:08 PM
Tiny
FISHERMAN
  • EXPERT
Hello !

Waoo! You`re good on pictures !

Well I have the schematic on my computer if I post it its going to loose its quality I`m Going to sed it to your mail and we can continue with the troubleshooting in here.

I`ll be around here. (Raining outside. Bad fishing day lol )
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Friday, January 4th, 2008 AT 6:03 PM
Tiny
FISHERMAN
  • EXPERT
Hello !

Well I was checking the diagram and by the connexion number (the color is different) the A1 Dark green-white (the brown on yours) feeds the fuel pump relay.
And the C1 black-Pink feeds the air control solenoid.

What do you think?

Let me know if you find the same codes.
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Friday, January 4th, 2008 AT 6:40 PM
Tiny
REALAMERICAN
  • MEMBER
Lets see, Mines A2, not A1. A2 is connected to the air conditioner relay. I dont know if it could burn out the ECM but I did have A/C problems. There was no current to the A/c relay before. I will have to check the wires on this to check for a cross. As for C1, where is the air control solenoid located? C2 says it goes to the 'air sw sol' what solenoid is this? And why doesnt my ECM plug have a wire for it?
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Friday, January 4th, 2008 AT 10:21 PM
Tiny
FISHERMAN
  • EXPERT
Hello.

I write down "air control Solenoid" on the search engine of the and shows "0" which means wont apply for your specific model the only option is a cross wire on the path of the A2 (A/C relay).

Question: is there other burn impress circuit that leads to the burnt chip? Or just those two?
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Friday, January 4th, 2008 AT 10:32 PM
Tiny
REALAMERICAN
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Its just two. If the air control solenoid does not apply to mine, what does the wire go to?
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Saturday, January 5th, 2008 AT 2:17 PM
Tiny
FISHERMAN
  • EXPERT
Hard to tell.

Anyhow check that wire and see if its grounded or shows voltage.

Same to the A2.
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Saturday, January 5th, 2008 AT 5:35 PM
Tiny
MASTERTECHTIM
  • EXPERT
I have a few suggestions. First if the timing keeps changing without the distributor moving your problem is the mainshaft in the distributor. Check for cracks around the reluctor wheel, that has to be why timing is changing. On the burning of the ecm check the resistance of every single solenoid, egr solenoid, diverter solenoids tcc solenoid etc. They must have a minimum of 20 ohms resistance or it acts like a dead short to ground.
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Saturday, January 5th, 2008 AT 6:50 PM
Tiny
FRANK TEIXIDO
  • MEMBER
Pictured two there is a piece of RV2 red color.
What is Component?
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Saturday, December 6th, 2014 AT 11:31 AM
Tiny
FRANK TEIXIDO
  • MEMBER
Varistor?
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Tuesday, December 9th, 2014 AT 3:09 AM
Tiny
FRANK TEIXIDO
  • MEMBER
Varistor 50V? = RV2
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Thursday, December 11th, 2014 AT 9:53 AM

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