OK as many of you know I am swapping my 1994 300 for a 1995 351. Motor is in and running waiting on cat back exhaust and a cutom tune on a dyno. I swapped the entire engine bay wiring harness from the 95 to my 94 and had to repin the transmission plug as well as the O2 sensor plug. All that seems to be working.

Now my problem..........speedomoeter is working but oil, temp, volt, and fuel are not. The button that puts the transmission into trailering mode is also not working. I am open to any and all reasonable suggestions on where to begin and what to do.

 

No Gauge cluster gurus on here anymore?

 

Check the Red/Yellow power wire. Mine (1992) had an issue with that breaking in 2, and caused the gauges to go all wonky.


On the cluster plugs, there should be 3-4 red/yellow wires. Go to the actual wire loom about 14" back into the dash and make sure it has power. Then if it has power, move on the cluster plugs and check for voltage.

Should be 12.5v?-ish.

 

When you repinned the bulkhead(firewall) connector, did you verify each wire's operation?

I had to do that when I used a 92 engine bay harness in my 89 F250. With no pin out listing for the 89 OR the 92 bulkhead connectors I had to chase each wire's function and repinned the 89's connector accordingly. I got every thing the 1'st time execpt the high beam indiactor is on with low beams and high too...... I'll figure that out later!


Other than that, check your fuses, sounds like one blew that supplies power to the cluster. There are two power feeds going to them.

 

Well I messed with it some today and found fuse 17 was blown. I replaced the fuse and turned the key on and the gauges looked like they were working. I started the truck and the fuse blew again. As far as repining the dash harness everything was a direct swap. The only thing I had to repin was the O2 sensor and the transmission where they break out of the engine bay. I could sure use a wiring diagram for fuse 17 and where all it goes. Not sure I understand why it works then blows when the motor is started.

 

Fuse 17 goes to: Tans Control indicator land and switch, stop lamp switch, warning chime, Instrument cluster and electronic shift control switch lamps(4x4)

Its a 10 amp fuse too.

 

What I have found and may or may not be 100 percent accurate is it is a Red/Yellow wire and it goes to the following. Of those 2 are from the tranny and I need to start there since that's the connectors I repined. Ill keep everyone updated.

Electronic Shift Control
Warning Chime
Transmission Control Module
Instrument Cluster
Brake Warning Resister/Diode Assembly RABS II

 

Just to keep everyone apprised of whats going on in case it helps anyone else. I put the fuse back in and turned the key to the on position without starting the truck and it looked OK so I started the truck with a screw driver at the solenoid and the fuse held. I believe I have it narrowed down to a red/green wire off the ignition switch. Getting closer if anyone has any ideas beyond this.

I did also put a digital multimeter on the fuse box and tested it in all key positions and the dumbfounding thing is there are no direct shorts to ground. It had resistance all the way. This makes it slightly more difficult to trace.

 

The entire path for that wire is "Key switch>Red w/ Green Stripe>Alternator/Battery Light>Green w/ Red Stripe (Alternator Excitor/"Turn On Wire") to the Alternator its' self.

 

This one is Red/ w green stripe. But I did check the alternator and its work perfect. The wire I am having trouble with I believe comes from the ignition switch to the ignition coil, to pin #4 on TFI and the EEC power relay. I am having trouble finding the EEC power relay though.

 

Re-Read my previous comment. I was half asleep when I typed it.

 

Ok I'll check that but in the interest of ultimate accuracy I tore the dash apart and looked behind the fuse box to see what was there. The wire is a red with yellow stripe on fuse 17. Now keep in mind it is hot and works fine until the key is turned to the start position eaning the red with yellow stripe is not grounded until the key goes from "on" to "start".

Now in getting this motor I took the engine bay wire harness from the donor truck but all the cab wiring is from the 1994 F150 300 I6. The donor was a 1995 F250 351W. I don't know if there is a wire that may be pinned wrong somewhere.

 

The link below is probably the closest to a resolution I am going to find though I am not a fan of buying multiple in line fuses. I am definitely open to ANY ideas.

http://www.justanswer.com/ford/0c8y9...need-know.html

 

So I decided to look at the 1994 harness and see what all the red/yellow went through and it goes to a heat shrinked splice with some resisters and diodes. This is not present on the 1995 harness or at least not anywhere near where it is on the 94. I then started tracing the wire through pins and on the 94 harness it goes through the main harness on the firewall but on the 95 it is a different color wire (green/yellow). Now I do not have the 95 dash harness so I can't tell you what it is supposed to do. A diode suggests a one way gate for electricity but I am at a complete loss as where to go from here.

So why in the heck can FORD not do crap the same on similar years? I am so sick of the little STUPID differences I am finding.

 

Do you have the E4OD transmission? As you repined the harness for the transmission, could of gotten a wire misplaced. With key on, engine off, does fuse 17 still blow? If not, and only does when starting, check the NSS(neutral safety switch) circuit.

Or do this, after the engine is running, replace that fuse and see what happens, if it does not blow, turn off the engine and restart it, it blows while starting, that narrows it down.

The resistor and diode you have in the harness is for the RABS Brake warning as shown on the schematics for the 94 F150.
Another thing is the OD switch circuit(TCS) may be pinned wrong.

For fuses blowing and they get expensive replacing them diagnosing a intermittant short. What I do, is pig tail a harness with male spade connectors(plug into the fuse holder) and run about 2' harness to a 1157 tail lamp/socket(or EQU lamp). What that does, if theres a short the lamp will light up brightly but will not fry anything!! It also gives a indication of the short occuring and saves fuses too! I have done this on TV sets power supplies but used 110V 60W lamps instead.

Depending on the power draw, the lamp will be dim , that's normal, At full bright is a problem.