34 Chevy Coupe 4.3L conversion AAUUGGHH post 11

[ktmoutfront]

Got moms car started today. Can not get the check engine light to turn off. No codes are shown. Running a 90 Astro ECM. Howell harness.

Question is, the Howell kit has 2 wires for the light. One is hot with ignition. The other one does not have continuity with ground or anything. Is the engine light supposed to be grounded?

 

[TheBeast_88K5]

I dunno...

But need pics of said moms car...

 

[73k5blazer]

I can't say for sure, but every GM ECM i've dealt with from the 80's and 90's has the check engine light circuit running from battery (power source..whatever, + power from somewhere) to light to ecm, and ecm will ground it to turn it on when there's an issue. So there should be constant power to the engine light, usually.

And yes, we need PICS!!!

 

[ktmoutfront]

Here is a picture from when I picked it up a year ago. And a crappy cell video from today. Go to the Photobucket link to see more. I started over but it looks the same. Just completely new.

http://s199.photobucket.com/albums/aa139/ktmoutfront/Dad n Moms 34 Chevy/

 

[ktmoutfront]

So if I am reading this correctly, the ground for the light is what turns it on and off? So I need to check that I did not ground that side of the light.

 

[max 02]

How cool is that!
Way to go Mom!

I guess you are building it for her but...sweet!

 

[80' 427]

So if I am reading this correctly, the ground for the light is what turns it on and off? So I need to check that I did not ground that side of the light.

GM loves to used switched grounds. Most of the new stuff is that way.

 

[63chevyll]

do you need me to print off a wiring diamram for you?

 

[zombie1969]

The ground comes from the pcm and on start up it turns the light on for a bit for a bulb check then turns off. The wire could be touching ground someplace or the pcm is bad.

 

[ktmoutfront]

Figured that out. The LED I am using I wired the ground to the high beam indicator ground. And the high beam indicator ground to the ECM.

 

[ktmoutfront]

So I had an issue with the car running fast idle. Then as the car warmed up, it would load up then run at 1800 rpm until it warmed up. Then it still ran at 1000 rpm.

Fought for 6.5 hours. Checking all kinds of crap. Vacuum lines, wires, sensors, you name it. Turns out, the Classic Instruments gage cluster has one common ground for the 4 gauges. The temp gauge was feeding back into the ECM and screwing with the computer. Put a 1 wire sending unit in the head, and it runs right. Calls to Howell and Classic Instruments was useless. They said it should work the way I had it. I hate aftermarket suppliers.

Rant off.

 

[63chevyll]

Ahhh, that makes since tho.

The temp signal is so Damn important on a speed density system like that.