im working on a truck for my brother it is a 99 cummins auto 4x4
it comes up with code 1689 truck is all stock with 275 on it
we swapped the ecm with one off a running truck and a tps of a running truck
didnt make no difference, truck only revs up to 1200 rpms but does start and run is there anything else that causes this code or is it the vp44??
thanks for any help

also all connections look good and harnes looks in good shape but i did not take it apart yet

 

P1689 No Comm between ECM & Inj Pump Mod
Its more than likely the VP. The only code that points to a bad ecm is 0606.

 

there is no other possibilities???

 

dam i have same code... sad day

 

Check the relay under the hood "Fuel pump Relay" Drivers side

When this relay is missing or broken the VP44 doesn't energize nor pump fuel. It allows you to do the cranking test. But it also sets a P1689 and CEL light. So for all of you that have a P1689 error code present check your fuel pump relay first by trading with another relay!


Do the above first before a VP44 replacement with a lift pump replacement.

 

so does this relay run the vp or fuel pump?

 

only other thing it could be is to check your connections on the back of the vp44, pull the clip and make sure they are clean and shiny, a bad connection could trip the code, however, since itll only rev to 1200, thats a fuel delivery problem and that means pretty much that the VP44 is dying rapidly. but like it was said, start cheap and simple first, check those relays andif it still has the problem, try to find a shop somewhere that has a VP44 tester and get it tested.

 

fuel pump relay is good, how do the shops test the vp44?

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i think it is just the vp