ECM Power
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
ECM Power
I am not one to track down power related issues on any vehicles, but I am the last stop for this car. I did some probing last night and discovered on the fuse panel the ECM is not getting any power. Took the fuse out and did a light test on the power side of the fuse, both with key on and off.
Can someone point me to a good wiring diagram so track the power source for the ECM?
Can I jump power from another line to the ECM just to see if it will fire up?
Thank you in advance.
Can someone point me to a good wiring diagram so track the power source for the ECM?
Can I jump power from another line to the ECM just to see if it will fire up?
Thank you in advance.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
I am not one to track down power related issues on any vehicles, but I am the last stop for this car. I did some probing last night and discovered on the fuse panel the ECM is not getting any power. Took the fuse out and did a light test on the power side of the fuse, both with key on and off.
Can someone point me to a good wiring diagram so track the power source for the ECM?
Can I jump power from another line to the ECM just to see if it will fire up?
Thank you in advance.
Can someone point me to a good wiring diagram so track the power source for the ECM?
Can I jump power from another line to the ECM just to see if it will fire up?
Thank you in advance.
Aside from that my best suggestion would be to buy the correct Factory Service Manual for your year.
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
http://www.chevythunder.com/198689_f...dy_1227165.htm
pnk/blk is hot when key on pin A6. Orange pin B1 is constant hot for memory.
pnk/blk is hot when key on pin A6. Orange pin B1 is constant hot for memory.
Last edited by MrWillys; Sep 13, 2013 at 08:53 PM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The ECM gets its power directly from the battery through a fusible link. It's the smaller wire attached to the positive battery terminal.
The other power input is from the ignition switch. This isn't really a "power" input -- it just tells the ECM when the ignition is on or off.
The other power input is from the ignition switch. This isn't really a "power" input -- it just tells the ECM when the ignition is on or off.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Fuse is on a Buss with the Pass Key and Injector Fuses so they should be dead too (or the buss is broken), or you have an ignition issue or the Fusible Link that feeds the Ignition is open. That link also feeds 7 non-ignition Circuits: Theft, Brake, LCD, Stop/Hazard, Pwy Acc, Hatch & Defogger (the latter three are Circuit Breakers). The only other cause is a dead battery. Service Manual Power Distribution is shown at the beginning of Section 8A; ECM Pinouts and functions are in 6E.
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
http://www.chevythunder.com/198689_f...dy_1227165.htm
pnk/blk is hot when key on pin A6. Orange pin B1 is constant hot for memory.
pnk/blk is hot when key on pin A6. Orange pin B1 is constant hot for memory.
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
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Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
Finally got power going to the ECM, which makes me think I need a new ECM in order to fix this car. Got a new one, plugged it in. Nothing still no spark to the plugs. I sure could use some help here. Could a bad ground cause this? If so where to start which ground wire to clean? I was using the sear frame on the passenger side as ground to do a fuse check, got good ground from the frame because I was able to complete the fuse check.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Finally got power going to the ECM, which makes me think I need a new ECM in order to fix this car. Got a new one, plugged it in. Nothing still no spark to the plugs. I sure could use some help here. Could a bad ground cause this? If so where to start which ground wire to clean? I was using the sear frame on the passenger side as ground to do a fuse check, got good ground from the frame because I was able to complete the fuse check.
Now you need to make sure you have ignition power at the distributor (pink wire). The pickup coil, ignition module and high voltage coil are what are now creating the spark. It is possible to have problems with the connections inside the distributor cap. Mainly that would be the high voltage coil ground and the connection from the coil to the rotor. I have heard several cases of the pickup coil breaking into pieces. Use a DVM to measure the resistance to verify that it is OK.
Last edited by Cliff Harris; Oct 11, 2013 at 12:40 AM.
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 799
Likes: 26
From: Lexington Park Maryland
Hence I thought that was it.
The initial check I did on the dist parts was the Iginition Module. Took it to Autozone, it was hooked up to their check machine for test. It checked out good. Now I must admit I have not verified the power going to the coil. I guess I am relying on the three garages that worked on this car before me they did the check. Since it is in my hands now I need to verify and eliminate that as a possibility. Thank you.