I need HELP. My car won't start

**blackcar** · 06-18-2012, 06:14 PM

Had the battery checked at autozone. Showed full charge 12.4 volts but bad battery. Put a new one in and it didn't help. Pulled the pump relay it looks clean put the jumper in and the pump comes on but won't start. Rechecked all important fuses. Hooked HPT up and it still can not connect to vcm.

How would I know if my PCM went bad while it was setting up???

I'm getting bad frustrated. I did all this work putting headers in, new motor mounts, new trans mount, new plug wires, new plugs, and removed the egr and air. And now it won't even start.

**pajeff02** · 06-18-2012, 06:29 PM

Are you still running a VATS bypass?

**blackcar** · 06-18-2012, 07:14 PM

yes,

Orion helped me figure out why my HPT is not connecting. My ground pin on the OBDII port is showing 8 volts with the key in run, 0 "ground" with the key off.

http://www.ls1.com/forums/f9/can-not...ct-vcm-166789/

How do I find out if it is in my PCM or a wire??

**blackcar** · 06-18-2012, 07:15 PM

Random thought. The O2 sensors are square could one of them be in wrong causing this??

**blackcar** · 06-18-2012, 07:19 PM

The wires at my starter looked like they had been hacked on but the starter turns over fine could it be there...

**0rion** · 06-18-2012, 10:57 PM

even though those connectors are square they will only click into place one way. If it was a starter wire your starter wouldn't turn the car over at all most likely. Need to get back to the main root cause of your problem. It still sounds like your fuel pump isn't priming correct? Have you physically checked pressure yet? If you check it and your have 58psi then you need to make sure you're getting spark. VATS kills the starter and the fuel pump both so if either one of those are working it's not a VATS issue.

**pajeff02** · 06-19-2012, 02:31 AM

I believe he is only getting the pump to come on when he jumps the relay harness. There would be 12 volts in the relay harness irrespective of VATS as that is probably killing the signal and not the power feed. So no spark and no fuel almost has to be a VATS issue.

Charles -- grab your DVOM and set it to read resistance. Probe the sides of your key chip and snap a picture of the reading for us. Then snap a picture of your resistor and how it is wired into your VATS harness.

**blackcar** · 06-19-2012, 05:55 AM

When the key is in RUN the ground for the fuel pump relay is 8 volts just like the ground pin on my OBDII port.

My VATS bypass is working. After I reset the PCM the security light went out. Tried to start the car with out the bypass. Car would not even turn over and the security light started blinking. It only took one resitor to get with in 50 ohms. I put it in and tried to start and the car would turn over and the security light went out.

Jeff If you really want me to get the pics for you I will. But I'm pretty good at wiring. Only student at SACC to make straight "A"'s in electronics. Unfortunately I only got to do one year.

I need to figure out why I'm getting 8 volts to ground with the key in RUN. If the signal wire coming to the fuel relay is showing 12 volts and the ground is showing 8 the relay is only "seeing" 4 and that may not be enough for it to kick in.

Not to mention all the other problems a 8volt ground can cause.

**pajeff02** · 06-19-2012, 08:28 AM

Ok -- wasn't sure and thought it would be an easy way to check things. I have faith in your abilities after you posted that.

Easy deal -- if you have 12.5 volts on your battery posts and less voltage down the line, it has to be a contact or wiring issue. Additional resistance caused by corrosion, poor connections or damage can result in what you are experiencing. Check your cable connections, especially by the starter, your engine grounds (there is one hidden on the back of the driver side head) and back probe power connections to isolate where the voltage drop is occurring. Our cars essentially go nuts when they have low voltage issues.

**blackcar** · 06-19-2012, 12:11 PM

My voltage is not dropping. I can put the red lead on the ground pin in the OBDII and the black on a ground bolt and it reads zero, like it should. Turn the key to run and it reads 8 volts. The ground wire has 8 volts. The hot wire still has 12. Some where I've get a short putting 8 volts in the computer ground (and the ground for the fuel pump relay) but not the chassis ground (and if I remember right not the ground for the starter relay).

But only when the key is in "run"

And Jeff no hard feelings. I know sometimes it is hard to tell if someone knows what they are talking about or not.

**0rion** · 06-19-2012, 03:00 PM

I've never tried checking shorts in a pcm but I wonder if you could check for continuity to ground like you do on every other kind of short?

**pajeff02** · 06-19-2012, 03:08 PM

Good idea -- probe the pin and a ground point with your ohm meter and see what you get. Compare that to the reading when you touch the probes firmly together.

**blackcar** · 06-20-2012, 06:30 AM

It will probably be this weekend before I can get back to working on it. Does anyone know where I can get a diagram of what wires are what coming out of the PCM?

**pajeff02** · 06-20-2012, 02:12 PM

I have the books for an '02. I assume they are the same, but not 100% on this. Anyone?

**cammed goat** · 06-20-2012, 04:31 PM

I'm thinking chafed/corroded ground as well. Possibly in the steering column/firewall area?

***Ed Blown Vert*** · 06-20-2012, 04:41 PM

Did you remove any grounds when you installed the headers??

**Smittro** · 06-20-2012, 04:43 PM

Or melt any grounds?

**cammed goat** · 06-20-2012, 04:49 PM

Originally Posted by Ed Blown Vert

Did you remove any grounds when you installed the headers??

Originally Posted by Smittro

Or melt any grounds?

Good questions. I have witnessed the carnage headers can do to wiring.

**Smittro** · 06-20-2012, 04:52 PM

Originally Posted by cammed goat

Good questions. I have witnessed the carnage headers can do to wiriing.

Headers get red hot on a regular basis (every time you go WOT) copper ground wire laying on a header will just melt right through.

**Smittro** · 06-20-2012, 04:56 PM

Never mind,, I had to go back to the begining and see he has'nt been able to run the car @ all.

My bad,, sorry 20,000 subscriptions can't remember all the first posts..