What will make my computer read no power going to it?

Tiny
MGLABAS
  • MEMBER
  • 1995 CHEVROLET TRUCK
  • 220,000 MILES
My truck was running rough and I couldn't even move it so I took the carb off and took it apart and thouroughly cleaned it. I put it all back togehter it ran better. Now you could move it a little ways then it started idleing up and down so I checked the cold start censor by unpluging it and then it ran smoother so I bought a new one and put it on the truck and it wouldn't crank the computer reading say that the computer isn't getting any power what will cause that
Sunday, December 11th, 2011 AT 2:38 AM

14 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
There has to be an open circuit between where you plug in and the PCM. Check wiring harness at PCM for corrosion, something loose, pushed in pins. Also, check IAC for idle issues.
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 2:52 AM
Tiny
MGLABAS
  • MEMBER
  • 8 POSTS
Hello I checked all my connections to the pcm and everything is fine no corrosion no pushed in pins and all the connectons were tight is there anything else that would make it read there is no power going to the pcm
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 8:38 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Where are you getting this information?
What is the code number/s you are seeing?
Your truck doesn't have a carb.
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 9:31 PM
Tiny
MGLABAS
  • MEMBER
  • 8 POSTS
12 is the code #
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 9:49 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
There is no code 12. You always get that code before it reads the real codes stored.
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 9:57 PM
Tiny
MGLABAS
  • MEMBER
  • 8 POSTS
It will run idling but when I put it in gear it idles down and shuts off it is a manual trans
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 10:03 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
First pull the EGR off and make sure it's not stuck open. At this point you could have issues with the throttle body, IAC, or many other things, especially since you have taken it apart now. You're not going to find this problem with a paper clip. That OBD1 system tracks only a fraction of what the newer computers track.
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 10:10 PM
Tiny
MGLABAS
  • MEMBER
  • 8 POSTS
When I took the throttle body off and cleaned everything I got new gaskets put it all back together and it ran better but I descovered the problem was the cold start censor and I replaced it then it wouldn't run right again I adjusted the timing and still the same problem the egr isn't stuck open any more suggestions
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 11:43 PM
Tiny
MGLABAS
  • MEMBER
  • 8 POSTS
Do you think it could be the coil or the distributer cap
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 11:46 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
There is no such thing as a "cold start sensor" so I don't know what you changed. It's probably time for a professional diagnosis.
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 11:47 PM
Tiny
MGLABAS
  • MEMBER
  • 8 POSTS
I changed the censor next to the thermostat housing
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 11:50 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
That's a coolant temp sensor that feeds the engine temp to the computer at all times.
Was this
answer
helpful?
Yes
No
Sunday, December 11th, 2011 AT 11:54 PM
Tiny
MGLABAS
  • MEMBER
  • 8 POSTS
I just started the truck in the dark and the coil is sparking would that cause it to run like that where you cant even drive it
Was this
answer
helpful?
Yes
No
Monday, December 12th, 2011 AT 12:04 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Of course it would.
Was this
answer
helpful?
Yes
No
Monday, December 12th, 2011 AT 12:09 AM

Please login or register to post a reply.

Related Engine Computer Content

Engine Computer
GUIDE
Engine Computer
The automotive engine computer, also known as the ECU, PCM or ECM (Engine control unit, Powertrain control module, Engine control module), is central to a vehicle’s ...
VIEW MORE