Does the PCM control power to the fuel pump?
- Thread starter Mark Depo
- Start date
I don't believe so. (But I could be wrong.) Power is controlled by a relay under the hood. It should just get constant 12 volt power. When you turn the ignition to "run" or "start", power is fed to the relay from the ignition switch, which in turn sends power to the fuel pump.
Consider looking at the wiring diagrams in the FSM if you're having issues:
https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
The diagrams will tell you exactly how it's wired
On mine when you turn on the ignition but don’t start the engine the pump will run for a couple of seconds until the pressure comes up and then shut off. So something is controlling it.
In a 2006 the fuel pump relay is controlled by the PCM. The fuel pump relay receives a constant 12VDC from fuse 12. The PCM sends a ground signal to the other side of the relay to energize/denergize the relay. PCM plug C3 pin 37.
Manual page 8W-30-3.
Manual page 8W-30-3.
I can usually hear the pump kick in on initial start sequence... then every once in a while I don’t hear it ....and now it’s just dies while going down the road... luckily it’s a sunny Sunday driver... but still.... where do I start?
If you are handy with a multimeter, you can walk through the circuit checking all wires......there is really only four wires , two fuses, and one relay to check.
1. 12VDC at fuel pump relay pin C6 from fuse box fuse 12 (with ignition switch on)
2. Ground at fuel pump relay pin C8 from PCM (with ignition switch on)
3. 12VDC at fuel pump relay pin C10 (from PDC fuse 23)
4. 12VDC at fuel pump pin 4 (with ignition on).
Refer to wiring diagram 8W-30-3.
All this info is based on 2006 model. If you have a different year, then you need to find it in the wiring diagrams and follow it through each leg.
1. 12VDC at fuel pump relay pin C6 from fuse box fuse 12 (with ignition switch on)
2. Ground at fuel pump relay pin C8 from PCM (with ignition switch on)
3. 12VDC at fuel pump relay pin C10 (from PDC fuse 23)
4. 12VDC at fuel pump pin 4 (with ignition on).
Refer to wiring diagram 8W-30-3.
All this info is based on 2006 model. If you have a different year, then you need to find it in the wiring diagrams and follow it through each leg.
Did you ever find a solution? I swapped the FUEL PUMP RELAY and the FUEL PUMP. Still same issue. The Fuel pump will run in accessory mode (Key turned on but not to start) for a long time. I turn it off, then proceed to turn it back on. The fuel pump runs, connects to relay (im assuming) and the Gas Gauge and Battery Gauge start to turn in the appropriate area. Then I can finally turn my jeep on.. Now that its colder, its taking about 30min to an hour for the gauges work.
Did you ever find a solution? I swapped the FUEL PUMP RELAY and the FUEL PUMP. Still same issue. The Fuel pump will run in accessory mode (Key turned on but not to start) for a long time. I turn it off, then proceed to turn it back on. The fuel pump runs, connects to relay (im assuming) and the Gas Gauge and Battery Gauge start to turn in the appropriate area. Then I can finally turn my jeep on.. Now that its colder, its taking about 30min to an hour for the gauges work.
yes, the PCM grounds the fuel pump relay coil, and the ignition switch provides the power side. This diagram is for my 99. The wire colors, numbers, and connectors differ on the 2006 but the circuit is effectively the same so I would expect it to be consistent in between.
Last edited:
That might be related to the ASD relay or circuit. Try swapping the ASD relay first and see what happens
Appreciate the suggestions. I changed all the fuses under the hood and glove box.