Just got a 1988 F250 4x4. The truck has few electrical issues that I am trying to take of. Tonight I was removing the trailer brake wiring. The trailer brake was electrical,. I found that the person that put it in had spliced in wires at several locations.

1. Wire one - green/red wire on brake pedal, single wire spliced in and new wire went to in cab trailer brake unit. Just removed the new wire left grm/red intact Right move ?

2. Under the dask to the upper left area above the brake there is a 6 wire connector that looks like it rides on a sliding round bar that goes through the fire wall. There was two red/blu wires. one of these wires was cut end left hanging that went back into the wire harness. other end was spliced and a wire was run through the firewall and out to the selonoid. I removed the new wire and reconnected the two ends. Right move? test wires no power is this the ABS system?

3. Rear of the truck wires that run between the tail lights. Brown wire was cut and sliced back together. There was what appeared to be hald of a fuseable link factory joined( rubberized 1 in two out) with this brown wire. Is there a fuseable link back there that is factory.

Truck has few issues but the price was right ! free

 

Yes, this was a wire that was hot at all times (LT GRN/RED).
The Red/Blue wire goes to the coil of the starter solenoid. I take it, it has a standard transmission and you are talking about a clutch switch.
I do not think they had ABS on an F250 in 88.
No, it is just a splice. The Brown wire is your marker lights.

 

I would guess that wire 1 is the brake light switch that tells the controller when you step on the pedal. If the second wire goes to the main lug of the solenoid and not the coil of the solenoid, I would say that was main power to the controller. I thought rear abs was standard on everything from 87-on...

 

I agree, the red/blue you messed with isn't for the brake controller, but for the neutral safety switch. Does it crank now? If it does, can you crank it in any gear(automatic) or crank it with the clutch pedal released(manual tranny)?

 

Manual trans., I just checked and now it wont crank. Clutch pedal down or out, nothing. I guess I should put this wire back like it was and try it then. Maybe there was an issue that the other owners had and this was there fix. The wire ran to the starter selonoid and attached to one of the small studs. I tested this wire at the selonoid and the cut ends both had no voltage! At the 6 pin connector this was the inside red/blue there was another red/blue next to it on the outside towards the firewall. Does this help to say what this 6 pin connector is?

Thats for the info so far.

 

I can't say exactly how this wire is routed. I can tell you electrically how it works, and then possibly you can figure it out from there.

The red/blue originates from the ignition switch. The ignition switch is mounted under the dash, on top of the steering column.

From the ignition switch it used to run over to a switch on the clutch pedal.

From the clutch pedal switch, it should run out through the firewall to the solenoid.

This wire stays the same color red/blue as it goes through all these components.

You will never have power on this wire unless you turn the key all the way to the start position. In the start position, the ignition switch under the dash sends 12 volts out to the clutch switch, and then to the starter solenoid to activiate the starter.

My guess is the clutch pedal switch went bad, so they bypassed it somehow.