Scanner wont link/ truck wont start/ Paypal reward
 

Ok this truck has been something else lol.


First off its a 99 Tahoe with a 5.7 automatic.
The truck does have air ride so it has been modified.
Since I got the truck there were starting issues. Hard to start but would start.

So getting more into it. I gave the truck a wire tuck. Moved the Pcm and fuse box and firewall plugs to inside of the truck.

Also removed a car alarm that didnt work I dont believe. Any wires that were removed from the alarm were just spliced onto the wire, meaning no stock wire was ever cut to add the alarm. The old connection have been resealed up.

So anyway, I get the wire tuck done. Go to start the truck and it runs for like 1-2 seconds then dies. will do this over and over.

Have 60psi at prime then drops to roughly 56ish psi after start up and die. Its a e2000 pump.

So after going threw all my wiring which is solder and heat shrunk, and was cut one wire at a time and labeled and or number. Everything looks good.

There were some plugs in the engine bay that were not hooked up like the washer bottle the abs stuff that I deleted from the truck, so i dont think thats it, cause the truck ran with out these plugs plugged in before.

So after a few days of searching and thinking maybe its the passlock, and trying to reset it which never worked. Truck still does the same thing.
Finally broke down and bought a obdII scanner and went to hook it up. Turned key to on then plugged in the scanner, it powers up but wont link.
So I tested the power and ground and they are both good. Then I ohm'd out the data link purple wire to the pcm and it reads out. I dont know the specs for that wire, but I got a reading meaning its connected.

Also I did noticed that the cluster lights did flash off and on but would stop.

Im lost on what it could be. I have welded on the truck battery disconnected.
I have added grounds and double check that all plugs are plugged in and all grounds are connected.All fuses are good. Although from sometime before I got the truck I did notice the horn relay is melted I have taken that relay out and the wires are not melted or anything.
Just lost really need some help lol.

If anyone can help me and actually figure this out Ill paypal ya a little something :)

Depending on what scanner you used ( if it was a cheap one from a parts store) it will only read the PCM/ECM. You could have codes in the BCM. Other than that, as much that has been changed it's gonna be pretty much trying to figure out what the last person did when they had it.

Will it stay running at all? My 96 had issue like yours except it would stay running most of the time. My issue (no applicable code, maf sensor circuit reference, couldn't get it to clear) the ecm wasn't reading the injector pulse all the time. Replaced it, problem solved. I know you removed the anti theft crap, but this issue also reaks of anti theft.

It's a acutron from auto zone was 140.00.
Previous owner just added the alarm. Other then that it was all stock.

Won't run now but a few seconds.

Think it could be from the pcm being unhooked so long?

I doubt it. With all the wireing/relocating stuff you've done, I'd revisit these things, and I know solder heat shrink, but relook at everything.

Hmm ill look at them again.
Just strange the scanner won't link to truck. Cause the port is getting power and the data link wire ohms out.

What was the reason for moving the PCM?

The truck has 24 inch wheels. Si had to redo the firewall for wheels to tuck.

obd not reading. only runs when scanner is plugged in thou. w.t
 

My 1998 /7.4 surberban,4x4 obd2 will not link. Only runs when a scanner is plugged in port. If i disconnect battery. I have to re hook up scanner, i turn key on
Off 5/6 or more times fast, and or push the lock unlock button 5 plus times. It resets the antitheft. And remeber mode. The Obd2 issue is mine also. But try getting a power probe and checking and marking (take notes) of the pins,power,grounds, and voltage. If you see something wrong (download) obd2 pin placement and schematics pdf for year make and model. Go thru everyone and you will find your problem. Good luck


First off its a 99 Tahoe with a 5.7 automatic.
The truck does have air ride so it has been modified.
Since I got the truck there were starting issues. Hard to start but would start.

So getting more into it. I gave the truck a wire tuck. Moved the Pcm and fuse box and firewall plugs to inside of the truck.

Also removed a car alarm that didnt work I dont believe. Any wires that were removed from the alarm were just spliced onto the wire, meaning no stock wire was ever cut to add the alarm. The old connection have been resealed up.

So anyway, I get the wire tuck done. Go to start the truck and it runs for like 1-2 seconds then dies. will do this over and over.

Have 60psi at prime then drops to roughly 56ish psi after start up and die. Its a e2000 pump.

So after going threw all my wiring which is solder and heat shrunk, and was cut one wire at a time and labeled and or number. Everything looks good.

There were some plugs in the engine bay that were not hooked up like the washer bottle the abs stuff that I deleted from the truck, so i dont think thats it, cause the truck ran with out these plugs plugged in before.

So after a few days of searching and thinking maybe its the passlock, and trying to reset it which never worked. Truck still does the same thing.
Finally broke down and bought a obdII scanner and went to hook it up. Turned key to on then plugged in the scanner, it powers up but wont link.
So I tested the power and ground and they are both good. Then I ohm'd out the data link purple wire to the pcm and it reads out. I dont know the specs for that wire, but I got a reading meaning its connected.

Also I did noticed that the cluster lights did flash off and on but would stop.

Im lost on what it could be. I have welded on the truck battery disconnected.
I have added grounds and double check that all plugs are plugged in and all grounds are connected.All fuses are good. Although from sometime before I got the truck I did notice the horn relay is melted I have taken that relay out and the wires are not melted or anything.
Just lost really need some help lol.

If anyone can help me and actually figure this out Ill paypal ya a little something :)[/QUOTE]