Hey everyone, hoping to get some advice before I start throwing more money at this.



My 2009 Hummer H3 cranks strong but won’t start because it’s not getting fuel. I pulled codes with an OBD-II reader and got U0109: Lost Communication with Fuel Pump Control Module A.



Here’s what I’ve done so far:

• Replaced the Fuel Pump Control Module (FPCM) with a new one — no change.
• Checked all the fuses and relays visually and with a meter — they’re fine (I can’t feel the relay clicking but does the V5 H3 even have a dedicated relay?)
• Probed the harness at the fuel pump: no voltage going to the pump.
• Tried bypassing/jumpering past the FPCM to the pump, and it still didn’t start.
• Probed the FPCM connector and it doesn’t seem to be getting power either.

So right now I’ve got:

• Good cranking, no fuel prime.
• U0109 stored.
• FPCM appears “dead” because it’s not receiving power feeds.

Has anyone run into this on an H3 or similar GM truck? What would you chase next — wiring harness from the fuse block, IGN relay, frame ground near the module, or something PCM-related?



Any tips or wiring diagrams would be hugely appreciated.

 

Check the integrity of the pump FPCM ground wire on the driver side of the rear cross member. IIRC there are three wires with ring terminals bolted to a stud on the cross member. This area is prone to corrosion.

Edit - looks like 2008 (attached) and 2009 (below) have a different control scheme.

Edit 2 - description of the 2009 fuel delivery system operation can be found --> here <--

 

i guess check fuses 29 and 54 under hood fuses.

 

This is a huge help. Would you happen to have the pin-out diagram for the ECM module?

 

maybe you can find something here
https://cardiagn.com/

 

All the information you need is available on the Charm.li website. It's an amazing source for factory service manuals for older vehicles.

2009 H3 3.7L Fuel Pressure Control Module Pinout

2009 H3 3.7L Engine Control Module Pinout

2009 H3 3.7L Factory Service Manual

On the hummer diagrams the connectors images are not showing correctly in the manual, but if you navigate over to the 2009 Chevy Colorado 3.7L section you can see them there:

Colorado ECU Pinout Diagram

 

The U0109 code on a Hummer H3 indicates a "Lost Communication with the Fuel Pump Control Module", meaning the Powertrain Control Module (PCM) can't communicate with the Fuel Pump Control Module (FPCM). Common causes include faulty wiring or connectors to the FPCM, a bad ground connection, a failing FPCM, or issues with other modules like the PCM or even a blown fuse...

I'm going to say faulty wiring or connectors , bad ground connection

 

Bad ground connections or faulty wiring, connector is a good guess. Follow the wiring from the fuel pump system... back to the front. Intermittently test the wire for signal and voltage/ground. I'm guessing you will discover something. Conversely you can trace the ground side to the frame. This needs to be broken down into small bite size morsels. If you just start panicky swapping parts it will make it more difficult to trace.
Have you removed and cleaned your ignition switch as HummerZ has offered so many times in different threads? Not saying this is the problem but I've seen some weird chit over the years..

 

My recommendation is he check the ground side of the FPCM to the frame. The frame ground for the FPCM is in an area that is prone to corrosion - on my 2009 H3 that lived most of its life in Ohio this area was badly corroded and all the ground wires at this frame location were internally corroded. I had to cut about 8" off of each wire to get back to good copper and splice in extensions to a new frame ground location. 99% this is the OP's problem.