wire harness to ECU connection - Lateral-g Forums

DaleTx · #1 09-04-2013, 08:25 PM

I am having a problem with the connection between my wire harness (red and blue) connectors and my GM ECU. I have 12 plus volts going into the ECU but the output lead from the ECU to the fuel pump measures only 9.8 volts. My fuel pump won't turn on with the low voltage, and the car won't start.

I suspect that I have a bad connection between the wire harness and the ECU. What can I do to improve the connection? The wire harness has been plugged in and unplugged several times and I think the connections are a bit loose now. The engine is a GM LS2 with a GM ECU.

I am looking for Ideas on how to restore a good connection between the wire harness (red and blue connectors) and the ECU. Thanks.

Vince@Meanstreets · #2 09-04-2013, 10:34 PM

Quote:

Originally Posted by DaleTx

I am having a problem with the connection between my wire harness (red and blue) connectors and my GM ECU. I have 12 plus volts going into the ECU but the output lead from the ECU to the fuel pump measures only 9.8 volts. My fuel pump won't turn on with the low voltage, and the car won't start.

I suspect that I have a bad connection between the wire harness and the ECU. What can I do to improve the connection? The wire harness has been plugged in and unplugged several times and I think the connections are a bit loose now. The engine is a GM LS2 with a GM ECU.

I am looking for Ideas on how to restore a good connection between the wire harness (red and blue connectors) and the ECU. Thanks.

Do you have that 9.8v lead going to the pump directly or to a relay? pictures please.

You can pull each pin out and carefully compress them with pliers.

DaleTx · #3 09-05-2013, 07:56 AM

Quote:

Originally Posted by Vince@MSperfab

Do you have that 9.8v lead going to the pump directly or to a relay? pictures please.

You can pull each pin out and carefully compress them with pliers.

I am running a Vaporworx DC controller and a GM CSTV fuel pump. I have one 12V connection directly from the battery to the 12V input on the DC controller, and a second "switched" 12V connection that goes from the ECU to the second "switched" input on the DC controller. Normally when I turn the key on you can hear the fuel pump turn on.

Yesterday when I tried to start the car... the fuel pump would not turn on. The trigger wire from the ECU measured only 9.8V. Next... I rigged up a switch from the battery with a full 12 volts and connected it to the DC controller and the fuel pump turned on... so I know the DC controller and fuel pump are working.

I think there must be a bad connection between the wiring harness and ECU. The voltage going into the ECU measures 12.5V. I'll try crimping the female connectors like you said and see if that fixes the problem. Is there some kind of gel or spray that you use on the connection that prevents corrosion or do you put them together dry?

Thanks Vince!

**Sieg** · #4 09-05-2013, 08:41 AM

DaleTx · #5 09-05-2013, 01:27 PM

Thanks Sieg... I'm going to make sure all the pin connections from the wire harness to ECU are good... and then use some of the dielectric lube on the connection to prevent future corrosion.

If this does not solve the low voltage problem... then I will have to go through each leg of the wiring harness to make sure there is not a short somewhere. The computer control engines are great when everthing is working properly, but not so good when things go wrong.

**CarlC** · #6 09-06-2013, 10:31 AM

Dale,

What about crimping a new terminal on to the wire that goes into the harness? I have some for the older Gen3/24T ECM's. I don't know if they work for the later Gen4.

There is very little power needed to turn on the VaporWorx controller. Less than a relay.

I just re-wired the whole car for the exact reason you mentioned. I hate things like this.

DaleTx · #7 09-06-2013, 08:18 PM

Quote:

Originally Posted by CarlC

Dale,

What about crimping a new terminal on to the wire that goes into the harness? I have some for the older Gen3/24T ECM's. I don't know if they work for the later Gen4.

There is very little power needed to turn on the VaporWorx controller. Less than a relay.

I just re-wired the whole car for the exact reason you mentioned. I hate things like this.

Thanks Carl.

I am also using a Gen3 24T/ECM. The VaporWorx digital controller will not turn on the fuel pump with only 9.8 volt input from the ECM. When I supply 12 volts to the digital controller the fuel pump does turn on, and maintains the correct fuel pressure. I know there is no problem with the VaporWorx controller or CTSV fuel pump... it's something else.

This weekend I will check all the power supply connections, ground connections, and the terminal connections between the wiring harness and ECM. Hopefully it will be something simple. It's a learning experience... at some point I may rewire the car like you did. Right now my car has a combination of old and new electrical circuits.