Another dilemma for the electrical gurus...

[unclehoser]

I've almost gotten all the electrical gremlins out of this truck, but still have one to conquer. 2002 F250, 7.3 Powerstroke, 6-speed ZF tranny:

My horn and cruise control still don't work. The fuse and all lamps are good. I've replaced the multi-function switch and clockspring. The control switches for cruise light up with instrument lights, as they should. There are connections to the brake and clutch master cylinders which appear to be in perfect condition. 'Third Eye' stop lamp works. No failure/warning indicators lit, no codes at OBDII port.

From what I can gather in the electrical manual, there is no separate speed control module on this truck, that function is solely contained in the powertrain control module.

What am I missing? I'm pulling my hair out...and there ain't enough of that as it is!!!

Any suggestions or comments welcome. You guys have been a big help so far, so I've come begging once more!

Thanks...
Dave

 

[79jasper]

Do you have access to autoenginuity?

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[unclehoser]

Sorry, amigo...I don't even know what that is!

OK...I do now. Scan-tool software. Unfortunately, no. The best I can come up with is a bluetooth-enabled OBD-II dongle and a $5 Torque app. If I did this sort of thing for a living, I'd buy the tools...but...there's the rub!

 

[79jasper]

I feel you there, but if keeping the truck for awhile, those software's can be very useful.
I know with AE you can do a cruise control diagnostic.
I don't think any of the phone apps will. Maybe car gauge pro.
Another one would maybe be forscan for a laptop.

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[unclehoser]

I'll take all of that to heart, and do a bit of research on the software, etc. I plan to keep the truck, but I'm by no means a "mechanic"! Just a DIYer who usually can 't afford to pay some other fool to fix things!

Thanks for the input...
Dave

 

[79jasper]

Cruise is built into the pcm.
It's odd for neither to work. Typically that points at the clockspring, but can mostly mark that off the list.
Maybe can get snicklas or someone else with a sd truck to see if they have any suggestions.

Have you tried ohming the buttons?

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[unclehoser]

That's my next direction...checking wiring harness continuity down the column, but, like I said, I just replaced the clockspring. Who knows...it could be a bad one, too! Wouldn't be the first time I got a bad part right outta the box! Of course, the horn switch is in the airbag assembly...those things give me the creeps to fool around with.

It's windy as hell here right now, and a rotten day to try to work on anything outdoors. 40 MPH or so gusts. Might try all that next weekend (my weekend is Monday/Tuesday).

I checked out the various software/interface packages online, and the best price I found on AutoEngiuity with the Ford/PSD package was about $350. I already own a laptop & a tablet, so that's covered. Maybe after I clear a few more financial obligations I'll take a closer look! It's all about the money, and I haven't hit the lottery yet!

Thanks again-
Dave

 

[snicklas]

Also, one thing on the AutoEnginuity..... it isn't just for the PSD's.... It will work with ALL vehicles, and you get the Ford enhanced bundle so you can do specific things with Ford's. It would work with both vehicles in you signature.... and let's say a family member has a 96 Honda Civic with a check engine light on. It would read it also..... You can spend a range on an AutoEnfinuity... for just the basic kit, to one with a single enhancement bundle (like the Ford Bundle) to one that has all the bundles to do all manufactures....

I WILL have an AutoEnginuity in the near future........

 

[unclehoser]

Agreed, it looks like a full-featured diagnostic tool, with the ability to grow to accommodate any vehicle you want to use it on. Definitely interested, I guess I need to start saving pennies!

 

[Double-S-Diesel]

for the cruise check the brake pressure switch on the master cylinder its a known failure part
should be closed with no pressure and open when brake applied.
other spot to check is the clutch pedal switch not sure of pins , but same thing closed when off of pedal.
the fact the dash is light ing makes me thing switchs etc ok

with scan tool you can look at the activations.

as for the horn , is the horn good, also I have seen the horn pad go bad.

 

[unclehoser]

for the cruise check the brake pressure switch on the master cylinder its a known failure part
should be closed with no pressure and open when brake applied.
other spot to check is the clutch pedal switch not sure of pins , but same thing closed when off of pedal.
the fact the dash is light ing makes me thing switchs etc ok

with scan tool you can look at the activations.

as for the horn , is the horn good, also I have seen the horn pad go bad.

I haven't checked the horn, physically, but I have checked the fuse that supplies both circuits. Continuity checks are next, when the wind stops enough to keep the doors from blowing shut on my legs! Damn, that hurts when you're up under the dash...

Thanks!
Dave

 

[unclehoser]

I'm revisiting this...took forever, but finally traced the problem! I had to remove the inner fender to tend to other issues, and discovered that the wires to the horn had been cut! Once spliced together, the horn still didn't work. I could hear the relay click when pushing on the horn switch on the steering wheel airbag insert, but no horn.

Fast forward to 2 days later driving to work: Accidentally hit the right button on the wheel and the cruise control activated! Worked as it should. So...I installed an aftermarket horn, and everything worked normally...for about a day. Then it all quit again.

Upon checking the fuse, I found it blown! I started to replace the fuse, and the horn blew constantly. Removed fuse, horn stopped. I disconnected the horn, and replaced the fuse. Pushed the horn switch on the airbag, and the relay stuck!!! Got it to release by playing around with the airbag, intermittently. Problem found. Bad switch.

New driver's airbags are $830 from Ford, and there's no way to repair the switch by itself. Found one on ebay from a recycler for less than 50 bucks...guess which route I'm taking!

 

[79jasper]

You can clean the buttons.


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[unclehoser]

You can clean the buttons.


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Well, in all honesty, I do believe that would be possible; however, after investigating the construction of said unit and evaluating the routes of ingress, I have determined that it would be in my best interests to not F*** with it!!!

As a young, crazy teenager I once relished the satisfaction of seeing things that I had cobbled together go "BOOM", but only from a distance! At this point, I can say that I've achieved life into my 60's because I have learned to avoid that behavior!

On the serious side...I was concerned from the outset about the lack of tactile response or "feel" of the horn pad. It was like whatever inside there that tells it to "spring back" to a normal position was worn or missing. My suspicions were confirmed when I was able to make it malfunction intermittently, and only with the slightest touch.

I think I'll just go with the $50 used part and avoid having something blow up in my face. My days of playing with homemade fireworks are over!

Cheers...
Dave

 

[79jasper]

Oh yeah. Working around the airbag. Lol

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