mazz140379

Hello everyone on LS1-tech!

I have a problem with my Camino. I planted a LQ9 out of a 2002 escalade in it and can't get it to start.
I shot a small video to present the problem:


So the fuel pump relay is clicking constantly. When it's clicking there is no connection between TAC and ECM. If I press the gas pedal all the way down before I turn on the ignition, there is no clicking and the connection is ok between TAC and ECM.
When testing the system with HP-tuners, priming the fuel system starts the clickin again.

I have used ECM- and TAC-modules, gas pedal and throttle body from the same donor car. Wiring harness is from PSI-performance.

I have made new ground wires all over the car, i have tried a new TAC and ECM-modules, i have changed the fuel pump relay, but nothing has changed the problem.

Any ideas what to check next?

lsxRanger94

The flooring of the gas pedal means you are trying to start the engine in "flooded" mode. The PCM will not *** anymore fuel until engine starts. the relay clicking is usually low voltage or bad ground. Make sure battery is fully charged and you have a constant 12v from PCM green wire during 2-3 second prime and once engine starts.

mazz140379

Thanks for the tips. I will check these on saturday.

Few more key points of the problem. There is no connection between gas pedal and throttle and the car won't start. The engine has fired few times, but has not run at all.

lsxRanger94

What do you mean no connection? you have not plugged in your harnesses?

bczee

iTrader: (12)

I would check the connections of the Relay and the fuel pump (grounds). I would also try another relay, usually when they are clicking like that, they are bad.

Check to make sure you are getting good battery voltage (fully charged battery) at the relay (term 30).

You can check tge wires to the pump by removing the relay and jump the sucket term 30 and 87. If the pump stays on. The wires should be good. (Bad relsy or PCM).

mazz140379

Thanks again!

No connection between gas pedal and throttle body means that, when I press gas pedal the throttle doesn't move. Hp tuners sees that the gas pedal is being pressed, but throttle doesn't react.

Relay has been replaced with a new one. Old and new tested in another vehicle and they both work fine.
Grounds triple checked. the last time I checked them, I made them all new. New grounds connect body to chassis, chassis to engine, front wing to body and battery to engine. PCM ground is connected to body. All surphases were cleaned with sandpaper and I put spring washers under the connectors.

aknovaman

iTrader: (7)

I take it your PCM is a red/blue PCM based upon your throttle body. Check continuity between the PCM red connector pin 9 (green/white stripe) to the fuel pump relay. Your harness looks like an aftermarket harness so the wire color may be different.

garys 68

iTrader: (1)

I'm thinking you might have 2 issues. I had a petal position sensor fail on my 02 LQ9. Sensor still registered position but alternate sensors in the pedal sensor triggered a failure and allowed idle only.
Try bypassing the relay (full 12V to pump) and see if it idles. Might even disconnect the pedal and try this. If it idles, your pedal position sensor might be the first issue.
Second find the fuel pump issue. Btw, you did trigger the relay with +12V from the ecu and not ground, correct?

aknovaman

iTrader: (7)

Red blue PCM fuel pump circuit diagram can be found here.


http://lt1swap.com/pictures/6_bcm_fuelpump.gif

oldcarguy85

iTrader: (2)

Did u ever solve this problem? I'm having the exact same symptoms with my lq9 dbw. Tried different tac modules, grounding, etc. when I disconnect the tac from the pcm I can scan it, but when connected relay clicks constantly. Seems like pcm is constantly In a reboot cycle.

lsxRanger94

Are you mixing and matching pedals, tacs,and pcm(corvette pedal, truck tac, ls1 computer or any other combo) or did everything come from the same truck?

oldcarguy85

iTrader: (2)

Everything matches the truck the harness/engine came from. Evrything I'd for an 02 escalade which is what the setup came from.

lsxRanger94

Something is creating a short to lock up the PCM if you can't scan when tac plugged in. Check throttle body, Tac, Tac to pedal harness, and pedal. Hopscotch it out. Unplug Tb with everything else plugged in and see if you can scan. Do the same for each component until you find the issue. Repair or replace wiring or component that is causing the issue.

oldcarguy85

iTrader: (2)

Ya it's hard to say yet. I think I really will have to trace every wire. With throttle body unplugged it still does it. With only the pcm> tac wire plugged in it does it. As soon as tac is unplugged all is good. I guess I'll start by tracing all the tac module wiring. This is a modified (by me) harness btw.

lsxRanger94

Only two wires goes from tac to PCM the rest go across engine harness to TB.

ls1nova71

iTrader: (4)

What are you using for a TAC to pedal harness? On an '02, the harness is part of the dash harness and not a separate harness like the '03-06. If you cut the ends and hooked them back together, are you absolutely sure they are hooked up right?

oldcarguy85

iTrader: (2)

I believe the tac>pedal harness is from a different truck. I've read mixed things about this harness. The consensus seems to be the wiring is 1-1 pin matching but some say pins e/j (or maybe e/k can't remeber) are swapped. I tried it both ways. I don't think my problem has anything to do with the tac>pedal wiring. With the pedal harness completely disconnected I still have the problem.

lsxRanger94

since you have swapped multiple tacs and does it with the tb connector removed, I'd check your harness pinouts for the tac module and check wiring to throttle body. Then check tune to make sure its setup for DBW

mazz140379

Hello guys!

Nice to see, that there's a lot of ideas! Unfortunately I spent my weekend sick in bed, so had no chance to love my Elky.
I will post updates as soon as I´m back in shape!

garys 68

iTrader: (1)

IIRC it is not 1 to one. One pair of wires in the pedal to tac harness are swapped on the 02 LQ9. Do you have the schematic?