I just recently purchased a 1993 7.3 non-turbo F350 crew cab w/a flat bed. I have been trying to troubleshoot what is going on with the cruise control. The servo is getting power to it with the key on through two wires. The column is getting power to the on/off buttons. Have checked the fuses under the dash and under the hood and all seem to be good. The reverse lights are not working; I can't find the answer to why they are not working; this is a standard transmission; and I have a feeling that the lack of reverse lights and the no cruise may be inter-related somehow...HELP!!!

 

I wonder if there is something wrong with the clutch switch? I have never worked on your type of truck, but most of the cruise control systems have a switch on the clutch that disengages the cruise if you push on the clutch pedal. Of course you have a switch on the brake pedal for the cruise too.

 

I am having trouble with the clutch switch; I've had to jerry rig it to get the pickup to start at present, however, the cruise was not working even prior to that. Including the steering column buttons, the brake and clutch switches, and the servo, are there any other components included in the system which might be bad? I would imagine there is a vehicle speed sensor somewhere; where is that located?

 

My knowlegde of C/C is for the 60's/70's.
It gets power from behind the cluster.
The amplifier is mounted to the inside firewall.


The guy with all the cruise control info is steve83.

Maybe do a search for *cruise control* and look for some of steve83's replies.


The System changed slightly in the late 80's from what I understand.
What year is yours?

 

It's a 1993. Nice 79', btw; I've got an early 78' I love as well.

 

I don't think they're related.

'93 was the first year for the electronic cruise servo on F-series, and the first year that the cruise VSS came from the RABS sensor in the rear axle. The quickest thing to check is the deactivator (brake pressure) switch on the L frame rail directly below the master cylinder. (Later models had it on the front of the MC.) It should have battery voltage to both wires at all times EXCEPT when you're pressing the brake pedal. If it's OK, test the Wh/Pk wire at the servo connector for the same voltage.

Next, check the R/LB wire at the servo connector for continuity to ground, and the Pu/Or wire for switched power from fuse E in the engine compartment fuse block.

To test the whole steering column circuit, put an Ohmmeter between the LB/Bk and DG/Or wires, then press&hold the OFF button on the steering wheel and rotate the wheel. The resistance should always be less than 1 Ohm. If it only fluctuates while you're turning the wheel, suspect the clock spring. If it's steady but high, suspect the control switches.

If all that checks out, pull the 1/2" bolt that holds the RABS sensor in the top of the axle & pull the sensor out. There's a small metal tip in the center that may be covered with metal filings. If it is, clean them off & prepare to rebuild your axle - something is probably wrong with it. The fill plug should also have a magnet, so check it.

If you're not familiar with any of the components I've mentioned, look through the photo albums in my sig link - you'll see many of them in the GP Auto pics album, but check the others, too. This site is also chock-full of good info & diagrams.

 

WOW! Thanks for the help, Steve! I'll be sure to let you know how it goes when I troubleshoot it.

 

Thanks for the information! I'll take a look and let you know what I find out.

 

If you have the brake pressure switch (it's red under the Master Cylinder or On it) - Mine whas be broke for evidently 3 years - I just found it on my truck F150 and there was a jumper in the connector??? - I pulled it out and Cruise Did not work...

I replaced the jumper wire back in the connector so I can have Cruise again...

I have never had any problems with this truck except recent overheating and foaming of E4od - ( New <20K Mikes)

My question is "Is the switch even worth replacing???" The cruise does shut off when I press the brakes... No problems with anything with the switch bypassed??? Do I spend to time and money on the stupid switch for the cruise that is working? Or is it tied into the PCM - Tranny control???

Changed fluid and filter on tranny - added aux cooler!! No more foaming out the TC Hole!!!

and yes the break lights still work with the switch disconnected and the jumper taped into it like it has been for 3 years.

 

That's a secondary kill switch for the clutch inside the cruise servo. The cruise also monitors the BOO (Brake On/Off) switch (the one on the pedal arm where the booster pushrod connects), so it can tell when to kill the cruise, but when that happens, the servo has to spin its motor to drop the throttle. The brake pressure switch (the red one in the hydraulic system) actually cuts power to the electromagnetic clutch, so the throttle falls IMMEDIATELY even if the servo doesn't respond for some reason.

I'd replace the pressure switch and wire it correctly. It can't be too expensive. If it costs more than $25 for a new one, contact me thru the classifieds.