Not getting 12 volts to F. Pump relay - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

67-LS1 · 10-20-2022, 08:38 PM

2013 LFX in my 66 Chevelle.
When I turn my key to the on position, I’m only getting 2.5 volts to the 86 terminal on my fuel pump relay. I have 12 volts at 87 and the pump is connected to 30.
This is a new problem out of the blue.
Any thoughts??
Fuel pump runs fine if I jumper to it.
Fuse is good and I changed it just to be safe.

gtstorey · 10-21-2022, 08:19 AM

Is this controlled by PWM? If not, have you confirmed whether the relay is controlled by a power signal or a ground.

Assuming its supposed to have 12v on that terminal, you are going to have to work your way up the chain to see where the voltage drops off. Do you have the wiring diagram for this circuit?

67-LS1 · 10-21-2022, 11:56 PM

It is not PWM. It should be straight 12v and I believe the signal is coming from the ECM. I’m tracing back now but was just wondering anyone else had had this issue.

67-LS1 · 10-28-2022, 08:09 PM

The wire is green/white strip and originates at the K20 X1 connector, terminal 44. It is supposed to be 12v as far as I can tell (circuit 465).
Everything had been working fine up until now?
Any clues?

gtstorey · 10-29-2022, 09:52 AM

The only diagrams I have access to are the 2010 models and that pin is not used on the v8 and is a low reference on the LLT. What is the description for that pin in the service manual?

10-20-2022, 08:38 PM	#1
67-LS1 Drives: 1966 Chevelle Join Date: Oct 2013 Location: Northern California Posts: 139	Not getting 12 volts to F. Pump relay 2013 LFX in my 66 Chevelle. When I turn my key to the on position, I’m only getting 2.5 volts to the 86 terminal on my fuel pump relay. I have 12 volts at 87 and the pump is connected to 30. This is a new problem out of the blue. Any thoughts?? Fuel pump runs fine if I jumper to it. Fuse is good and I changed it just to be safe. __________________ 66 Chevelle with 2013 LFX V6, 6 speed auto, full Hotchkis suspension, Wilwood 4 wheel discs.

10-21-2022, 11:56 PM	#3
67-LS1 Drives: 1966 Chevelle Join Date: Oct 2013 Location: Northern California Posts: 139	It is not PWM. It should be straight 12v and I believe the signal is coming from the ECM. I’m tracing back now but was just wondering anyone else had had this issue. __________________ 66 Chevelle with 2013 LFX V6, 6 speed auto, full Hotchkis suspension, Wilwood 4 wheel discs.

10-28-2022, 08:09 PM	#4
67-LS1 Drives: 1966 Chevelle Join Date: Oct 2013 Location: Northern California Posts: 139	The wire is green/white strip and originates at the K20 X1 connector, terminal 44. It is supposed to be 12v as far as I can tell (circuit 465). Everything had been working fine up until now? Any clues? __________________ 66 Chevelle with 2013 LFX V6, 6 speed auto, full Hotchkis suspension, Wilwood 4 wheel discs.

10-21-2022, 08:19 AM	#2
gtstorey Drives: 2010 Camaro SS2,L99, LSA SC Join Date: Aug 2017 Location: Huntsville, AL Posts: 2,142	Is this controlled by PWM? If not, have you confirmed whether the relay is controlled by a power signal or a ground. Assuming its supposed to have 12v on that terminal, you are going to have to work your way up the chain to see where the voltage drops off. Do you have the wiring diagram for this circuit?

10-29-2022, 09:52 AM	#5
gtstorey Drives: 2010 Camaro SS2,L99, LSA SC Join Date: Aug 2017 Location: Huntsville, AL Posts: 2,142	The only diagrams I have access to are the 2010 models and that pin is not used on the v8 and is a low reference on the LLT. What is the description for that pin in the service manual?