1996 Ford F 150 4.9 L6

IAC,MAF IAT DPFE CRK SENSORS ALL IGNITION SYSTEM MAIN PCM DIODE PCM FUSES RELAYS ALL POWER UP FINE and all lights internal and external all work properly

the engine starts and runs fine with a self provided ground to the fuel pump relay where the lt/blue - orange wire plugs in on the relay thats the fuel pump control wire going into the pcm

toadyboy1957 wrote: the engine starts and runs fine with a self provided ground to the fuel pump relay where the lt/blue - orange wire plugs in on the relay thats the fuel pump control wire going into the pcm

If everything else works, then I think you're looking at a simple failed driver OR there was a short to power on the light blue/orange wire, either from a wiring problem, or a shorted relay coil. Either way, it seems like the damage has been done.

Have you tried driving around with the fuel pump relay control jumped? Ran well? Honestly, if this was my truck, I'd be REALLY tempted to wire a rocker switch into that light blue/orange wire and put it on the dash. :whistle: You could even hide it somewhere, and now you've got a cheap anti-theft system! :lol:

And not to forget to check current travelling through this "jumper"

wuth the jumper wire grounded it starts runs well and drives all day long but soon as i disconnect the ground wire and hook the lt/blue orange wire the fuel pump control is gone its running 3 amps thru the jumper wire

i could switch the ground wire and have a cheap anti theft system as well

A relay consuming 3 amps of current at 12 volts? Looks like a lot to me.

how much is normal on a circuit feeding tjhe relays the inertia switch then the two fuel pumps??

I thought you was jumpering only LB/O wire in that case you only jump relay control which i don't know exact numbers but 200mA at max i think

the LB/O GOING INTO THE PCM is the dead wIre so i ran the GROUND from where that LB/O was supposed to be / left the LB/O COMPLETELY DISCONNECTED AND TAPED UNSIDE THE BOTTOM OF THE FUSEBLOCK GROUNDED THE RELAY AND IT NOW RUNS LIKE A SCALDED DOG LOL neither o2 sensor works heater circuits are good and have no grounds to any of the 3 soolenoids on the back right side of the valve cover

Three amps on that relay control wire? borntoroll is right, that does sound abnormally high. If that relay coil is shorted, then it'd certainly explain a failed driver. But not the other inoperative components.

Are there any other similar relays that you could borrow from another system? Mostly I'm interested in comparing the current draw of the fuel pump relay compared to another. If they're both three amps, then I guess that's normal. If it's significantly less, then I'd say that relay is bad.

Do you have a scanner available? If all those outputs are dead, then I'd suggest running the KOEO and KOER self-test, and see what codes you get back. Those tests will force the PCM to use all it's outputs, and should flag codes for inoperative stuff.

i do not have a scanner im just a poor DIYER IM SO SORRY

I did get the short in fuse 16 fixed tho ome less problem to deal with YES FUSE 16 IS A FIX YEA/

i switched relays with the trailer relay in the underhood relay retested current is now 300 milliamp i bought a new relay and retested again is same about 300 milliamp // second confirmed FIX FIX FIX AND AGAIN THANKS FOR ALL YOUR ASSISTANCE TO EVERYONE HERE

it looks to me like the U 20A fuse sends power to the PCM Power relay on the R/LG wire in the start/run position. That closes the relay and sends power to PCM and fuel pump relay. Meaning the red is power so the LB/O is ground. So if you put the key in just the RUN (without starting the truck) position you should be getting 12V to the red wire on the fuel pump relay. If the fuel pump relay is NOT being turned on then the 12V should be just flowing through the coil and down the LB/O wire. So Im thinking that if you put the key in the RUN position then you should be able to measure 12v on the LB/O wire at the fuel pump relay. Then measure that same wire at the PCM. if you don't see 12V or anything less than 12V you know you have a break in the wire or corrosion. Could there be corrosion at the Test conn pin 6?

THIS IS THE ONLY PROBLEM I STILL HAVE/// the LB/O GOING INTO THE PCM is the dead wIre so i ran the GROUND from where that LB/O was supposed to be / left the LB/O COMPLETELY DISCONNECTED AND TAPED UNSIDE THE BOTTOM OF THE FUSEBLOCK GROUNDED THE RELAY AND IT NOW RUNS LIKE A SCALDED DOG LOL neither o2 sensor works heater circuits are good and have no grounds to any of the 3 soolenoids on the back right side of the valve cover

THIS IS MORE LIKE A LONG LONG CASE STUYDY NO SIMPLE FIX

toadyboy1957 wrote: i switched relays with the trailer relay in the underhood relay retested current is now 300 milliamp i bought a new relay and retested again is same about 300 milliamp // second confirmed FIX FIX FIX AND AGAIN THANKS FOR ALL YOUR ASSISTANCE TO EVERYONE HERE

Sweet! :woohoo: Dare I say we're getting somewhere?

I think the shorted relay probably accounts the cooked fuel pump relay driver. You could remove the PCM and look for burned components on the circuit board, but I think a replacement PCM would be the better way to go.

The other outputs that don't work may require more testing to verify. No worries about not having a scanner, sir. Just trying to think of ways to make the job easier.

That's what I was getting to also with what I said. If he can verify it is a bad driver for the fuel pump relay then he can get a new pcm. I would verify one problem before I move to the next. Maybe the new pcm (if he needs one) would also fix the other problems

AS FAR AS THE O2 SENSORS GO THE HEATER CIRCUITS HAVE BEEN CHECKED FOR SIGNAL FROM THE PCM ALL IS GOOD THERE THE 12 VOLTS TO THE O2 SENSORS ALSO VERIFIED GOOD THE ONLY THING MISSING IS THE GROUNDS FOR THE O2 SENSORS THE SWITCHED SOLENOIDS ON THE VALVE COVER ALSO HAVE NO GROUNDS BUT I CAN PROVIDE THOSE GROUNDS WITH 1 WIRE THAT IS NO PROBLEM DONT KNOW HOW LONG THOSE HAVE HAD NO GROUNDS