I set up a FASS pump last year and used the power for my original transfer pump to energize my new relay for the FASS,so the truck died on me yesterday the transfer pump quit,I switch the fuel system relay,engine control fuses no luck still didn't have power,I got it going again by running a wire on a switch straight from the battery to energize my FASS relay and it works fine for now as long as I don't forget to turn it on or off,in the service manual it shows a 10 amp fuse run/start just can't find it could that be the cause?

ECM fuel pump control circuit failed. You'll have to have the ECM sent in and rebuilt.

There should be a fuse in the Fass wiring harness. My AD has one. That is the only fuse for the transfer pump. The power from the ECM is unfused. Have you checked to see if the lead from the ECM is hot while the engine is running? You can also bump the starter, no engine start, and the lead should be hot for 20 seconds or so.

I wonder if the power is hooked to the battery and rotted off? Another common issue.

38 minutes ago, Mopar1973Man said:

I wonder if the power is hooked to the battery and rotted off? Another common issue.

Lets hope @wagntagn knows. Sounds like he installed it.

so I checked the lead(deutz connector)original plug for the transfer pump and nothing when I crank the engine and even tried bumping the starter and no luck,this was my lead to energize my Fass pump relay,so with the switch I installed straight from the battery truck runs fine,I guess the original lead is straight from the ecm? In the manual page 873 it shows fuse 9 run/start (10 amp) in junction box it looks as it sends power to the ecm when starting is that correct?For the ecm if I need to get it repaired who rebuilds them should I send it to the dodge dealer?For now I should probably be ok with my switch I just flick it on before I start the truck and off after I stop the truck.

What's the average $ for an ecm rebuild?

Not sure the dealer does them anymore and if the do it will be quite spendy. Here is some places with known success.

You would have to speak with the vendor to find out about cost.

This morning was cool 34 F the truck started ok with my switch and the grit heater was cycling as normal ,which pin on the ecm is the fuel pump?maybe the lead wire from the ecm is the problem?

According to the wiring diagrams the power comes from pin 15 and pin 35. I dont know why it comes from 2 sources. When you get this deep into the wiring I have to step aside and let the more knowledgeable step in. 

 

Is it possible to check the lead that powers the transfer pump at the ecm?one thing I read in the service manual that when cranking the transfer pump is running at 25% that means the way I had it wired I only had 25% of my voltage cranking not sure if that was enough to engage the relay on the FASS pump maybe using the lead from the ecm isn't the best?What's the best way to hook up a Fass pump?

What it does is flick it on and off quickly. It still gives it 12v just on off, on off. When it is working you can pull the fuel system relay and just crank the engine and you will here the Fass relay clicking on and off. It keeps the pressure down for VP while starting.

Your right I noticed that too 15 & 35,probably one is cranking 25%  and the other one running 100 %.these would be the outputs of the ecm to the transfer pump,back to page 873 the fuse 9 in junction box(run/start) feeds pin 5 on the ecm would this one be for the transfer pump?

So the way I wired my Fass is ok,tomorow I'll check fuse 9  in junction box that feeds pin 5.Good info on that wiring map, easy to troubleshoot with the colors.