ECM wiring harness concern?

Reply

  #1  
Old 08-28-17, 08:32 AM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
ECM wiring harness concern?

I have a 1988 Chevy Silverado C3500 ext cab, with a 454 tbi. I was changing the ecm, and noticed that one of the wires had about 2" cut out of it. I was hoping someone might be able to tell me for sure if I should repair it, or leave it as is, before I put in the new ecm?
 
Attached Images  

Last edited by daddyzaring229; 08-28-17 at 09:14 AM. Reason: adding image
Sponsored Links
  #2  
Old 08-28-17, 11:10 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,227
Received 478 Votes on 448 Posts
It's extremely rare to see a piece of wire cut out of a wiring harness like that from the factory. You would have to consult a service manual to see what that wire was used for
 
  #3  
Old 08-28-17, 12:10 PM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
Well, I am at least the 2nd owner. I bought it from a guy that hauled horse trailers and hay trailers. I didn't figure it was done factory like that, because they would have capped it off or whatever, at least you'd think they would. LOL
 
  #4  
Old 08-28-17, 02:55 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,227
Received 478 Votes on 448 Posts
If the vehicle is running without it connected.... there shouldn't be an issue.
 
  #5  
Old 08-28-17, 03:09 PM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
It ran, until the motor reach running temp. Then it would die any time I let off the gas. Which is why I was changing the ECM. That was the last thing to try and fix that problem.
 
  #6  
Old 08-28-17, 04:34 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,227
Received 478 Votes on 448 Posts
Did you have the ECM checked for trouble codes ?
The problem with randomly replacing ECM's is that they need to be programmed for the vehicle they are used in or in some you swap the PROM chip.

If your problem was anything like my Ford had..... it was a defective pickup module inside the distributor. When it got hot... it went intermittent.

I would doubt you have an ECM problem.
 
  #7  
Old 08-28-17, 08:28 PM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
Autozone said they had no way to check it. It has the PROM chips out of the old one. It ran fine when I first got it, until it started going through belts, and I had to replace some stuff there, including the water pump. Then it started dieing all the time, because the tbi had a leaky gasket, and it runs fine now until the motor reaches running temp., or it did before I pulled the ecm to replace. I have reinstalled yet, waiting to find out more about this wire.
 
  #8  
Old 08-29-17, 03:53 AM
Member
Join Date: Aug 2015
Location: USA
Posts: 506
Received 9 Votes on 8 Posts
having a bad ecm wasn't to uncommon for early gm vehicles they failed a lot more than most other manufacturers still could be a lot of things that could cause the engine to die though like ignition or even a sticking egr valve.
 
  #9  
Old 08-29-17, 07:41 AM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
The reason for changing the ecm is because it had been dieing once the motor reached temp. It would run just fine while it was cool, but when it got warmed up I would have to keep my foot in the gas or it would die. I had everything else checked, and fixed, so this was the last thing to do that it could be.
 
  #10  
Old 08-29-17, 10:23 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,227
Received 478 Votes on 448 Posts
when it got warmed up I would have to keep my foot in the gas or it would die.
That does not sound like an ECM problem to me.
More like an EGR problem..... or possible idle speed control/motor
 
  #11  
Old 08-29-17, 11:30 PM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
Well mainly what I am trying to find out is if I should reconnect the wire that has about 2" cut out of it. I found a diagram, but I'm not sure what color it is. It looked brow with white stripe to me, but there's no wires that color on this diagram.
 
Attached Images  
  #12  
Old 09-07-17, 01:11 PM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
So would the egr valve or idle speed control/motor cause it to die after it reaches normal engine temp? It runs just fine, until the engine reaches 210 degrees.
 
  #13  
Old 09-07-17, 02:29 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,227
Received 478 Votes on 448 Posts
Can you list the colors to either side of the cut wire ?
Maybe 3 wires.... the cut wire and then another 3 wires.
I'm looking at several different ECM diagrams.
 
  #14  
Old 09-07-17, 06:19 PM
Member
Join Date: Aug 2015
Location: USA
Posts: 506
Received 9 Votes on 8 Posts
you can remove the vacuum line to the egr to see if there is a difference, I would expect the iac valve may cause issues long before the engine got that warm also, maybe a better description of the problem the engine dies but it restarts does it idle?
you getting any codes from the ecm?
 
  #15  
Old 09-07-17, 06:26 PM
Member
Thread Starter
Join Date: Mar 2016
Location: United States
Posts: 14
Received 0 Votes on 0 Posts
PJMAX, I got home from work kind of late tonight, but as soon as I get time and good light, I will figure those colors out if I can for you.

alan73, It will start and run fine until the engine reach normal temp of 210, and if I let off the gas it dies. It will usually start right back up, but if I don't keep my foot a little into the gas pedal it will just die again until it has completely cooled down.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: