casias

iTrader: (1)

I am really getting frustrated. I installed a stand alone harness that was new, and included a fuse and relay panel. Following all of the instructions below, I have all of the wires I want to use connected. The fuel pump won't prime when the key is turned.

Any ideas? I am sure it is something simple.

Thanks

33willys

iTrader: (1)

First, can you jump a hot wire to the fuel pump and get it to run? I don't mean at the pump itself but the wire that comes from the fuel pump relay to the pump? If yes, then is there power to the fuel pump relay with the key "on"? Does the relay go to ground when the key is "on"? Usually the problem is a ground wire not hoked up but you could have a relay power problem or bad relay.

casias

iTrader: (1)

I haven't tried pulling the relay and bypassing it. From what I read on the "net", do I jump 30 to 87 with a jumper wire?

64post

iTrader: (5)

Yes, 30 to 87 bridged bypasses relay low amperage switching functions (85, 86). Check to see if 30 is hot at all times, it should be.

TomM

iTrader: (56)

Is this a PSI harness?


T,

casias

iTrader: (1)

No. I got it from BP Automotive.

So here is what I did today.

1) Jumped fuel pump socket 30 to 87, and fuel pump ran fine. Generated 60 psi on my adjustable regulator.
2) Jumped Fan 1 socket 30 to 87, fan ran fine.
3) Tested all fuses. With ignition off, the PCM IGN, Sensor, Bank 1, and Bank 2 fuses have no voltage. When ignition is on, all fuses have voltage.
4) Disconnected Ignition lead from start/run source and connected directly to 12v. Ensured voltage on all fuses. Tested fuel pump and fan again by jumping sockets.

The ECU remains undetectable by my scanner, and does not trigger fuel pump or throttle blade movement.

Any thoughts?

Edit: If VATS was not disabled, would the ECU not respond at all? I thought it would wake up normally, but only allow the engine to run for a few seconds. Just a thought.

ls1nova71

iTrader: (4)

Pull the fuel pump relay and check to make sure youre getting 12v on either 85 or 86 for the two seconds when the key is first turned (people wire them different from time to time) and make sure the other one is a ground.

ls1nova71

iTrader: (4)

If you can see the wires under the relay, the wire youre looking for on 85 or 86 will usually be dark green.

casias

iTrader: (1)

Ok. I will try that. I can remove the bottom of the fuse box and flip it over to see the wires.

Project GatTagO

iTrader: (7)

Do you mind posting a couple of pictures of how that lid attaches to the fuze base?

Andrew

casias

iTrader: (1)

Not sure I follow, but here is the fuse box with the lids on. The blue arrow points at the lid in question.

Project GatTagO

iTrader: (7)

See how the other two lids have the metal clips? The one that the arrow is pointing to has a different method of securing the lid...I am curious how it snaps to the base, since there are no metal clips like on the other ones...

Andrew

casias

iTrader: (1)

If you look real close, it just has "squeeze" type plastic clips on each side (green circle).

casias

iTrader: (1)

For anyone who may come across this thread with a similar problem, I am going to post the solution.

After several hours and several phone calls, I was told to check the following wires on the 73-way ECM connector. Special thanks to lt1swap.com for providing really good information about ls swap wiring.

1) Pin 19 switched ignition 12v (had that)
2) Pin 20 constant 12v (had that)
3) Pin 47 switched ignition 12v (did not have power)
4) Pin 73 ground

So I noticed that pin 47 did not have power, but had a pink wire to it.

So I applied power to the pin and the ECU woke up, throttle body, fuel pump activation, and the engine started. Didn't run good on it's tune, but did start and run.

Since the wiring harness was already deeply installed in the system, I wasn't about to remove it to see where the problem was, so I fished a wire down next to the harness and cut into it just behind the ECM connector, adding switched power to that pin. No more problems.

It's just frustrating to buy a brand new custom harness that is defective.

L92 OLDS

And another example of why I am saving $1400 and making my own. So far, I'll admit it's been time consuming but I'm not stuck with some aftermarket cookie cutter harness with a crappy relay and fuse center. I'm glad you figured it out....

casias

iTrader: (1)

Yeah. I didn't want to learn wiring, but now that I have, I will probably just do my own next time.

blackbyrd

iTrader: (14)

Thank you for bringing this thread up. I have been having an o2 issue for the past year and I just realized that my stand alone harness has a fuse block that I have not checked.

I was about to repin the harness so I could run a 99+ harness. suppose I should check the fuses first......

67 C10 LS

Bringing this back up as I'm having similar issues. Fuel pump relay is not getting 12v on 85. 86 is ground. Checked the following pins as mentioned earlier in this thread and they all match as below.

1) Pin 19 switched ignition 12v (had that)
2) Pin 20 constant 12v (had that)
3) Pin 47 switched ignition 12v (had that)
4) Pin 73 ground (had that)

I have verified fuel pump works by hooking power directly to it. 2006 LQ4, harness is factory cut down by Adam at lsxharness. ECM programming by LT1swap. Engine turns over just won't cycle fuel pump with key on. ECM has power as I can connect with scan tool.

I'm lost on where to check next, any help is appreciated.