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2002 3500 Cab/Chassis Secondary Pump Relay

n4hmr
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n4hmr Enthusiast

n4hmr

Posted
Posted

Hello -



I may be in the wrong forum here, but the questions may apply here also.



I have a 2002 Chevy Silverado 3500 Cab/Chassis truck (not an HD), VIN 1GBJC34U22F129260, 6.0L engine with dual tanks - Front/rear.



I am trying to get the rear tank working. I have the wiring diagrams for this truck but cannot find the physical Secondary Pump relay. Looked under the hood - only saw 1 relay labeled F/PMP. Nada found on either end of the dash panel.



Where is this relay located? Anybody know?



Fred




n4hmr Enthusiast

n4hmr

Posted
  • Author
Posted

Shoulda posted this diagram in the 1st post - but I didn't. So here it is.

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post-156169-0-88976700-1459917129_thumb.gif

post-156169-0-88976700-1459917129_thumb.gif

post-156169-0-88976700-1459917129_thumb.gif

davester Senior Enthusiast

davester

Posted
Posted

maybe at the rear junction box, inside left-hand frame rail at the very back? The FP2 harness might plug in there. or at least check around the frame where the aux fuel pump harness goes from the tank to the frame.

n4hmr Enthusiast

n4hmr

Posted
  • Author
Posted

Finally figured out where it is! Plowed thru the GM DVD again & found more nuggets. It is attached (or was) to the motor side cover of the Electrical Center. It had become disloged from it's home and was hidden under a couple of the harnesses. But that's where it lives.

 

Now the only thing I have to find out is whether or not I can safely ground pin 86 on that beast to force pick the relay. Pin 86 is the grounding signal from the PCM to start up the rear pump. Usually you can safely apply an external ground to points that are 'ground driven' because the feeding circuitry typically has a high impedance circuit that more or less ignores the externally applied ground.

 

So, does anyone kow if manually applying a ground to that relay Pin 86 to force it to pick is an approved test procedure?

  • 3 years later...
Bmfb New Member

Bmfb

Posted
Posted

Could you explain in more laymen’s terms where you found the plug at? 

  • 3 months later...
  • 9 months later...
Teri Sanders New Member

Teri Sanders

Posted
Posted
On 4/5/2016 at 9:13 PM, n4hmr said:

Hello -

 

 

 

 

I may be in the wrong forum here, but the questions may apply here also.

 

 

 

 

 

I have a 2002 Chevy Silverado 3500 Cab/Chassis truck (not an HD), VIN 1GBJC34U22F129260, 6.0L engine with dual tanks - Front/rear.

 

 

 

 

 

I am trying to get the rear tank working. I have the wiring diagrams for this truck but cannot find the physical Secondary Pump relay. Looked under the hood - only saw 1 relay labeled F/PMP. Nada found on either end of the dash panel.

 

 

 

 

 

Where is this relay located? Anybody know?

 

 

 

 

Hi, you mentioned you had a complete wiring diagram, so you still or where did you find it? In desperate need! Please let me know asap

-Teri 

760-522-3877 

Fred

 

 

 

 

 

 

 

 

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