I hope Injuneer or someone else very knowledgeable is online because I could use help quick. The problem.

The Z28 drivetrain is in the 96 RS Camaro I bought. It's all connected and turns over but won't start. I diagnosed it to the fuel pump relay is not getting triggered by the line from the PCM (dk green/white wire) The Fuel pump relay is good and if I jumper it I can hear the fuel pump whir.

The details. When the 3.8 was in the car it cranked and ran. I'm using the same key, key cylinder, etc, so the key pellet should be good and matched to the car. The car does turn over but isn't getting fuel. Am I gonna have to get the 50 HZ adapter? I have an portable O-scope so I'll probably try to look at the signal to see if it's there. I forget where that 50 HZ signal comes from.

I have the Torquehead 24X kit installed thus I have a 98+ PCM in the car. It ran just fine in my '95Z

I'm gonna check if the security light is on and maybe try the VATS resistor bypass but I'm suspecting there is a difference in the 95 V-8 engine harness and the 96 3.8 engine harness. That's where I'm hoping someone knows where to look. So everything worked together before (engine, PCM harness) the difference is it's in the 96 RS so the dash wiring is probably the difference. To reiterate, the fuel pump relay connector is getting B= on the orange wire to the relay connector, the ground is good and the grey wire to the fuel pump is good. To repeat myself I jumpered the orange B+ to the grey and the fuel pump runs. All fuses are good.

I'm supposed to take the car to the dealer early in the morning to get aligned but will have to cancel if I can't solve this.

I hope you can help me until then, call me "Still looking"

 

The chassis harness connections vary from year to year, so you may have to repin the engine harness connectors to match. If you haven’t already address this issue, Shoebox has a table of the engine harness connector faces for 1993-1997. But those are for the V8 engine. I don't think the V6 would have the same pinouts. You could check by comparing the V8 and V6 harness connectors in the 1995 and 1996 factory service manual.

You can download a complete 1995 and 1996 manuals here, courtesy of GaryDoug.

https://www.mediafire.com/?40mfgeoe4ctti

Not sure how the 24x conversion affects this. Note that in 95 the key pellet was read by the “Theft Deterrent Module” (TCM), which sends the 50Hz “fuel enable” signal to the PCM. In 1996 that function was incorporated into the Body Control Module. May need to move the TDM from your 95 to the 96, and rig the wiring correctly.

 

95 TDR:

http://shbox.com/1/pass_key.jpg

96 BCM:

http://shbox.com/1/bcm_1996.jpg

Key words are “fuel enable (signal)”

 

Spent the evening comparing 1995 5.7 Harness with 96 3.8 harness. Tomorrow I look to see how the match at the car.

 

I've found quite a few wiring differences at C210, C220, and C239 where the engine harness connects to the dashboard harness. I started to begin adding and changing the affected wires but stopped. I wonder if it would be easier and cleaner to get a '96 engine harness. I know compared to the '95 harness it will have a cam sensor and crank sensor that I won't need. How would this affect the swap? Is it introducing more problems then it may solve?

If I proceed with adding/rerouting wires it looks like it will be necessary to change/add wiring at the PCM connectors which makes me nervous. Unfortunately, I'm at a gotta keep going and work this out situation as there is no retreat. I suppose one way would be to find a '95Z body to put my drivetrain into.

Input is appreciated.

 

Did you also consider the issue of the 95 sending the “fuel enable” signal to the PCM from the TDM (which the 96 RS chassis doesn’t have) and the 96 sending it from the BCM (which the 96 chassis has). That has to be corrected, or a 50 Hz module installed.

 

I had read where you mentioned that previously but I don't know how to address it. I hadn't heard about the 50HZ adapter until I started researching this problem in the forums. I'm guessing the 50HZ module sounds like the easier solution.

Do you think a 96 harness would help this correction or can I stick with the 95 harness and add the 50hz module?

 

I'm pretty sure VATS has been deleted in my PCM program. I'll need to get my reader connected to verify but if so, how would that affect things. In reading about the VATS Bypass Module from Hawks, the ad seems to imply that if the PCM has been reprogrammed to remove VATS, the module wouldn't be needed.

 

If PASS-Key II was correctly "deleted" in the PCM, you would no longer need the "fuel enable signal". As I mentioned above "Not sure how the 24x conversion affects this."

I have no idea about the details of the differences in the 95 and 96 chassis harness interfaces. Shoebox has the V8 pinouts. I would assume there are differences between the V6 and V8 chassis side connectors. I assume you are using a custom engine harness for the 24X conversion. What chassis did they base that on?

 

The only harness difference with the 24X system in the use of an LSI PCM from TH. The PCM from TH is a P/N TH411PCMOBD1M, S/N TH411-389135. I don't know how different it is from a regular LS1 PCM. I'd have to ask, if I can get them to reply.
The same/orginal LT1 engine harness is used but the center connector of the PCM is used to connect the PCM to the fuel injectors. (I've emailed them asking for a pinout of their PCM but haven't heard back yet. If I recall correctly the security light is not showing on my dash instrument panel.

I have the pinout from SHbox. I'm using the 96 service manual from the link you provide from Gary Doug and the schematics from my Haynes manual to trace wiring. I have downloaded the 95 Service Manual so I can use the two GM manuals to compare connector connections.

I definitely am not getting the fuel enable signal to the fuel pump relay confirmed by voltage checks. Additionally, I jumpered B+ from the IGN connection on the fuse box to the relay and the fuel pump is activating when the key is turned to ignition. Thus relays and wiring is good from the FP relay back.

The 3.8 dash connector is wired differently from the 95 engine harness. Maybe I just need to get the fuel enable connection right. I'll try that when I can.

 

The stock harness has a fuel pump prime connector to test for operation. You don’t need to jumper the relay to check the pump. OK for checking the relay..

http://shbox.com/1/fuel_pump_prime.jpg

It would seem to me if PASS-Key II (VATS) was deleted from the PCM, the fuel enable signal should not be required. That's the only interface of VATS to the PCM. When I posted recently that the PCM needed the fuel enable signal to restart the fuel pump, GaryDoug corrected me and said his LT1 simulator setup cuts the injectors, not the pump, when it doesn’t get the fuel enable.

 

I appreciate the additional information and the clarification.

Perhaps I'm incorrect about the VATS being disabled in the PCM. I still have not heard from anyone at Torqhead.

I am definitely not getting the voltage to energize the relay solenoid to provide power to the pump. I wanted to ensure the relay and following wiring, and with my Racetronix fuel pump there is a second relay near the tank, was all good. That's why I disconnected the wire (Dk Grn/White) coming from the PCM that is the fuel pump relay enable, and provided an alternate supply from the IGN B+ from the fuse panel. Doing that, the relay energized and I could hear the pump spin up, but the car still would not start.

I realize I may/do have other problems to correct but I'm focusing on getting the fuel pump to run when I try to start the engine. I have much to check including if the injectors are being energized and if I have spark for two.

I'm on vacation for a week so I won't have anything to report until I get back.

 

I heard back from Paul, owner of Torqhead, this week. This is what he had to say regarding the pinout of the PCM they supply with their kit.

"Our PCM has identical pinout to a 1994-1997 LT1 PCM. This is for the red, blue, black and clear PCM connectors. You can reference it off the 1996 manual you have for PCM pinout and that will work. Fuel pump relay control is Red connector Pin #7."

He goes on to say that he believes my problem does lie with the differences in the connectors between the engine harness and the dash harness.