Thomas Moody

Let me start by saying hello everyone, I have a 2004 Heritage F150 with a 4.6l engine and automatic that I have been trying to fix for some time and am at a total loss.
The problems :

Cranks but won't start, the fuel pump is new and it will not prime like it is supposed to. I have no fuel pressure at the rail. If I bypass the relay I get 39PSI at the rail so I know it is good. I have 6.88 volts out of the relay and have tried several relays all with the same results. However I think there is more to it than that.

My gauge cluster does not work either by this I mean no needle gauges work, idiot lights all work but that is it. I turn the key and not a single needle moves from 0. Also the mileage (odometer) doesn't illuminate. I have checked every fuse, relay, ground, fuseable link and all seem to be good. In the back of the cluster there are two plugs and only one of them is getting power.

I have a scan tool on my PC that I use for my F250 diesel that allows testing of circuits but when I connect it to the obd port I get a communication error when trying to test the fuel system, can bus circuit, Instrument cluster test and GEM system test

What I have done, replaced sensors, alternator, PCM, relays, fuel pump, inspected every diode, capacitor and solder connection on the cluster main board. I have removed every ground I could find and cleaned the surfaces and re-tightened

I am completly at a loss for what else I can do. The history is I would drive down the road and the gauges would stop working a few minutes after they stop working the truck would stall out. I could usually get it to start back up but the last time it did it I had to have it towed home and it hasn't started since. Any help or ideas would be greatly appreciated

My thought is that because the gauges don't work the PCM has shut down the engine due to no oil pressure. Just a thought and maybe totally wrong.

Jbrew

You have a bad short or just as bad ground issue. I'd start with the direct PCM ground, then catch all grounds in the cab behind the kick panels. Then the cab/frame grounding strap underneath (they rot in two). Then all grounds on the Firewall and at the fuse blocks. Solder cracks in the clusters are common as well. Re-heat and questionable joints.

These issues can be a bunch a fun, fortunately you end up figuring it out in the end...eventually. Good Luck.

white89gt

Exactly. Time to get out the scope on a rope. Just to kind of give you a starting point, check out these videos.

Thomas Moody

Thanks for your input, I have unscrewed/cleaned and tightened every ground in this truck that I could find. Under the dash (behind both kick panels) behind the battery on the firewall on the frame to cab, so unless I missed one or two I did what I could find. I also re soldered the instrument cluster, the only thing I found wrong was the pins going to the odometer had come loose. Could this be a bad GEM causing the gauges not to work?

white89gt

Does/Did it ever wig out on you? Dash lights flashing on and off, gauges pulsing, relays clicking on and off under the dash, windows won't roll down/up, wipers not working, washer fluid not spraying.... or has it ever tried to start itself? Any other weird things happen, making it look like it is possessed?

Thomas Moody

Wipers don't work, but everything else seems to work. Light are on when the key is on and I don't have DRL.

Stu Cazzo

Stab in the dark here...it almost sounds like an alternator issue.
All the wonky electrical things going on point to a burnt out or defective diode in the alternator.

Thomas Moody

I have replaced the alternator

fordguy2100

Ah but new parts don't always mean properly working. Have you verified new one is working as it should? Parts nowadays come from China and it's not rare to have a bad part right out of the box (or a failing part)

Aragorn

I'll second this and even if it passes the test doesn't mean it's good. Went through three of the bastards to find a good one on the ex wife's escape 2 years ago.