Strange Power relay reseting

[JoeHarlan80]

First I will share I have a new lift pump and TPPS and crank sensor. this truck has the modifyed relay installed a few years ago. Today I had time so I put a test light to the Red and Green wire key on power source for the FP relay and also powers the VP 44 pump as far as I understand. When the engine is cycling off the power to the red/green wire goes away. there are no codes present at this time Adding short video.  I'll add its a 1999 2500 with auto

 

Thanks for any help.

Edited August 23, 2021 by JoeHarlan80

[Tractorman]

41 minutes ago, JoeHarlan80 said:

this truck has the modifyed relay installed a few years ago.

 

I am assuming this is a relay for the fuel transfer pump.  This relay should get its power to the coil portion of the relay from the ECM - yellow/whit wire that used to be directly wired to the fuel transfer pump.  A fused circuit from the battery should go to the load portion of the relay.  This relay should power only the fuel transfer pump.

 

41 minutes ago, JoeHarlan80 said:

Today I had time so I put a test light to the Red and Green wire key on power source for the FP relay and also powers the VP 44 pump as far as I understand.

 

Since you have identified a red/green wire on this relay, I believe you are talking about the fuel pump relay in the power distribution panel.  This relay supplies power to the VP44 only.  The power to the coil portion of the relay comes from the ECM - a  brown/white wire.  The ground for the coil is a black wire and is grounded on the left inner fender area.   This ground is important.   Fuse #3 (20 amp) in the power distribution panel supplies power to the load portion of the relay via a red/white wire.   

 

Can you confirm what I have written?

 

- John

 

Edited August 23, 2021 by Tractorman

[JoeHarlan80]

2 minutes ago, Tractorman said:

 

I am assuming this is a relay for the fuel transfer pump.  This relay should get its power to the coil portion of the relay from the ECM - yellow/whit wire that used to be directly wired to the fuel transfer pump.  A fused circuit from the battery should go to the load portion of the relay.

 

 

Since you have identified a red/green wire on this relay, I believe you are talking about the fuel pump relay in the power distribution panel.  This relay supplies power to the VP44 only.  The power to the coil portion of the relay comes from the ECM - a  brown/white wire.  The ground for the coil is a black wire and grounded on the left inner fender area.   This ground is important.   Fuse #3 (20 amp) in the power distribution panel supplies power to the load portion of the relay vial a red/white wire.   

 

Can you confirm what I have written?

 

- John

 

Correct on all items I will confirm the ground wire in the morning.

 

[Tractorman]

Here is a diagram of the fuel pump relay circuit.  Note that there is a joint connector in the PDC in the grounding circuit.  

 

- John

 

[Mopar1973Man]

WAIT TO START light coming on instantly?

[JoeHarlan80]

Yes,wait to start instantly most everytime and as you can see in video blinks on with every reset like full power loss.

[JoeHarlan80]

ok finally threw a 1689 code..

 

[Mopar1973Man]

Ummm... not during running when you key on for start.

 

As for ECM and VP44 pump share the same ground on the passenger side battery.

 

Highly suggest the W-T ground wire mod for your truck.

 

Also check the PDC fuses. It possible to have them Crack and randomly shutdown as the fuse opens and then close again. Ive seen that before.

[JoeHarlan80]

I went through the full checkout on the code. it appears it is being set when the power cycles on this circuit. one more bit of info is that when you hold this long enough for the engine to die the dash appears to lose power the lift pump stops running and the injector pump loses power. leave the key in the on position and I hear a relay click and power returns.

[Mopar1973Man]

+12V power fuse for both the PCM and ECM... Again like I said it could crack and do this random cut off. Fuse #2 also check fuse #10 being it feeds the KEY ON signal.

 

Then the other fuse for key on trigger for both the ECM and PCM here is the other end of fuse #10. Be aware that is not our fuel pump relay it for the GAS series. 

 

Then for the VP44 you need to check Fuse #3 in the PDC.

[JoeHarlan80]

Thank you again Ill go inspect all of these.