Ok Gents. I've been a member for years and have used the forum search to fix many-a-problem, but this one has me stumped. I have a 95 LT-1 automatic that won't start. No click at the starter. (brand new starter) The security light stays on when I have the key turned to the run position. If I turn the key to the run position and get under the car and place (jumper)screwdriver on the starter between the hot battery terminal and the hot solenoid terminal the car starts and runs perfectly for 3 seconds every time then dies. I installed the VATS bypass module today and it made no difference. The only code I'm getting is H53. Any ideas?

 

The VATS bypass module provides a signal to the computer emulating the key and this should allow the engine to crank. You need to trace power from the ign sw crank terminal (gets 12v in crank position) which goes to the start enable relay contacts, then to the gear selector switch at the base of the gear shift lever, then through the firewall connector to the starter solenoid terminal on the starter.
I would first see if you have 12v on the gear selector switch in park when the ign sw is in crank position. If you don't then you should see if the start enable relay is closed and 12v passes through the relay contacts. If the relay isn't closed, then either the VATS bypass isn't working/not connected properly or the computer is suspect.

 

Thanks for th reply jfb.I replace the starter, alternator, ignition module near the coil, ignition switch on the steering colum, starter relay and d.a.b. relay, transmission range (neutral-safety) switch. I checked to see if the coil is getting 12v and it is. The yellow wire on the transmission range switch puts out 12v when the key is turned to the crank position. Still no start. Looks like I have to find the theft deterrent relay and relay control. I think they are somewhere under the passenger side dash.

 

It was the VATS... AND... I needed to reset the PKE after installing the VATS bypass. So.... I replaced a million parts and it still wouldn't start. Just for grins and giggles, I decided to turn the PKE system on and off 3 times... just to see. Now it cranks and runs like a champ!!!

 

I am wondering which module you got H53 from whether 1 or 4. Because if it is Module 1 (CCM), it is a pass-key error (historic). That might make it VATS related.

If the error code is from module 4 (PCM), then it is a over voltage condition related to the PCM. Looks like it will shutdown many PCM functions. Since the alternator is not running over voltage cannot exist because the highest voltage you can get is battery voltage. However it is a historic code so could have happened while engine was running at some time.

Please recheck the codes to get the correct related module. If I were to guess, I would think it is from module 1. Record all codes and then clear them and see if any returns.

If you really have a error code 51, it could activate VATS and FEDS. This error code relates to the pass-key output voltage pin of the CCM. FSM says it's an open or a short…great. Could be defective lock cylinder falling apart on the pellet contacts part of it. Either no contact or shorting it to ground.

If this actually and really is a problem, a VATS bypass might not help you.

For starters, I would get to the connector contacts at the base of the column and open connector up. Check back up to the key and see if you can measure the proper resistance of the key pellet while key is in the cylinder. Also check to ground for a short.

Then check back up towards the CCM and see if you have 5 volts on the WHT/BLK wire. The return wire is PPL/WHT. Measure across these two wires. Have key to on when doing this and don't short the pins to ground. I am not sure the return is a chassis ground potential. (per my 94 FSM).

Don’t forget, it takes 3 minutes for VATS to reset according to the FSM.

If I had to guess at your 3 second run time when you kick the starter, it sounds like the fuel (injectors) is being shut off which relates to FEDS.

In short, if VATS in the CCM is not happy, then there is no handshake on the serial bus between the CCM and PCM. If the PCM does not get the password and is not happy, it then shuts the injectors down.


**Darn

Well I wrote all of this and you snuck in on me. Hope it stays fixed. Maybe you can use my info in the future.

 

How did you do this??

 

Have 96 LT1 automatic and would not start when engine was hot.
Starter would not turn over. After huge tow bills, and checking out every thing I found the problem. First I changed relays under the carpet lower dash (under the steering wheel) relays are in a row...just change them all. Nuetral switch in console...nasty job, then the key problems by cutting the VAT system wires and soldered in the correct resistance as key was measured with ohm meter.
Replaced starter with Bosch starter (crap anyway as then the true problem came out) A guy told me they were partly made in China, and
can not take the heat from the exhuast system. Wrapped the exhaust pipe with fiberglass wrap and the starter then with aluminum cover for water protection as a heat shield. (do not touch the wire terminals on the starter with metalic alum. Now runs great. Maybe use Delco starter as replacement but may be the same as Bosch. I put new batteries in all my cars every 3 years if needed or not. Store with battery tender charge all winter in heated
garage. Runs perfect now.

 

what were the function of the relays that you replaced? How were they related to the starting system and/or key on or VATS?

 

I did not check out what they were but after turning the ignition ket to start and
replaceing them all I finally got a click and power from the relay that was not functioning.
the wiring diagram in the manual is very poor, so I did alot of trial and error work.

 

I replaced everything and when the key is turned the relays click. Manual does not
show their function (after market manual)

 

What does the start enable look like, and where is it located? Also what does the VATS module look like?
Thanks,

 

That $75 FSM is lookin real nice about now....