'95, F150 Speed Control quit working
 

I just recently got my '95, F150, Ext. Cab, 4wd, 5.8 up and running. So far, it's been doing well considering that it has been in the garage for 2.5 years, with the engine out.
​​​​​​
I took it for a long drive a week ago and the Speed Control worked fine. Well, fast forward to Tuesday this past week and now I don't have Speed Control. I have checked every fuse from the Engine compartment to the cab fuses and everything is good. Now, the truck has the Ford issued Recall on the Master cylinder. Fuse is fine. I checked the Brake pressure switch that is mounted on the Master and it isn't Open.

​​​​​​I also have verified the Horn work's, the Airbag light isn't flashing, the O/D cancel switch works and isn't blinking. All the brake lights work, including the one mounted on the cab.

I have checked the Cruise Control Servo Amplifier and I don't have power coming in on the Purple/Orange wire through the connector.

I appreciate any help. Thanks again everyone!

The Purple/Orange wire is powered by fuse "E". Check both sides of the fuse "E" with a loading test light.

If the fuse was bad, then I shouldn't have power to the HEGO sensor or the ABS Control Module, correct?

Thanks again Subford for your quick reply!!

Nevermind!!!
You were right Subford!!!!
Just explained why I got DTC 172 as well. Fuse was blown. In my haste, I only checked one side of the fuse.. ughhh

Your awesome! Thanks again!!

Ok...

So it seems there is a short on the Purple/Orange wire that is only associated with the Speed Control.
The new 15amp fuse blew just after I pushed the button.

Any ideas where to start looking Subford?

Thanks so much!

Just open the wire at all the items that fuse "E" supplies then plug one back in one at a time until the fuse blows then you have found the problem.
More than likely a short in the wiring harness along and under the passenger side exhaust manifold that is supplying power to the O2 sensor.
Attachment 287489

/

I checked the harness for the O2 sensor and it ohmed out fine. I was thinking the O2 harness as well.

I will keep looking.

Thanks so much!

I unplugged everything all sensors and connectors associated with Fuse E (Purple/Orange) wire Except for the MLPS. Installed the 3rd fuse, started the truck, had power on both legs of the fuse. Put truck in gear, checked fuse and it was blown. Never tried the Speed Control function.

Does this point to a bad MLPS? The wiring looks fine going to it. Nothing out of the ordinary. I'm stumped.

It would be a bad TR sensor (old name MLPS) or the wiring to it.

That's what I'm thinking.

I was able to narrow down when the fuse blows. Anytime I shift from Park to Reverse or from Neutral to Reverse.
When Reverse is selected, the fuse blows immediately.

I noticed transmission fluid around the housing of the TR sensor. I'm gonna pull it tomorrow and see what it looks like.

Right now the ABS light is flashing and I can't move the shifter from Park to Reverse if it's illuminated. If I turn the key back and the cluster goes out, then I can select all gears, but I can't move the shifter From Neutral to Park if the key is turned to the Start position.

This all just started after troubleshooting today. I haven't had any problems before with the shifter moving in all gears with the key in the Start position.

I'm up for any ideas come tomorrow.

​​​​

Shift lock:
Attachment 287488
/

I removed the harness from the TR. Found 6 exposed wires. Repaired them. Same thing. I installed a new TR sensor, same thing.

I also jumpered the (BK/pink) #6 to (Purple/orange) #7. That blows the fuse immediately. I checked for continuity between the BK/pink in the TR sensor all the way back to the plug for the lights themselves and there's no short.

Now, I have lost the Horn function. Fuse is good and I have checked both sides and there is power coming in and out, but the Horn has ceased to work. The airbag light isn't flashing and it comes on momentarily each time I turn the key to start.

I also have the solenoid pack wiring disconnected as it had several exposed wires just above the connector. I have since fixed that, but haven't plugged it back in.

What am I missing here??

Do you have factory trailer wiring?
If so the Battery charge wire circuit may be shorted to ground.

Yes. I removed the "T" Grey plug at the rear and eliminated it for the time being.

This morning I checked the 5 pin grey male connector at the rear between the 16 pin connector located on the driver side inner fender well for on the (BK/pink) wire. It's open.
If I check the black/pink wire from the TR sensor to the 16 pin connector under the hood, it shows continuity.
If I check the TR sensor to the rear 5 pin plug it's open.

I may be on to something, hopefully.

Thanks Subford!

You might try pulling the Trailer Battery Charge relay and see if the fuse still blows.