So I've searched and read and read and searched.

I have no horn, no cruise.

I have lights on the steering wheel switches fine.

I measured all the resistances for the steering wheel switches, and checked the horn switch as it goes into the clockspring, everything checked out fine.

Replaced the clockspring, no joy. Cracked open the old one, not a hint of any problem.

Checked voltages and resistances at the cruise/servo module, fine.

Took the servo module thingy and swapped it with my truck. Works just fine in my truck. My trucks doesn't work in the X.

If I try to get the module to go into its self test mode by turning it on/off while holding the off switch, I can get it to blink on the dash, but the next switch presses bring no more blinks.

I have continuity and a dry master cylinder switch.

I have a working top center brake light, fuse tests ok.

I'm stumped.

 

The only thing I can find so far is there is a diag test of pin 4 to pin 10 at the servo connector for resistance. I get 41ohms on the X, the sheet says over 20 you need to go look at the bpp and that checks out, so then to the cpp switch or jumper.

Is there a cpp jumper on these? The bpp goes into a bundle and off into the firewall.

I take the servo control box over to the super duty and it will do the self test fine, wont blink at all on the dash in the X beyond holding the off switch and turning the key to on.

I see everything else as it should be on all the tests I can find, other than this 41ohms. Its 21 ohms on the superduty.

 

from pin 4 to 10 i get 12v during brake pedal press, 0 with no brake pedal press. Seems this would be the critical test but...

 

have you checked the ground connections? the cruise grounds at the front of the right front fender.

DOE

 

checking resistance from pin 10 to ground i get 0, I'll see if I can find the actual ground.

I also have no trailer running lights, and no horn. I've got an electrical mess and I'm not able to make any progress it seems.

 

from all your information above. you do not indicate if you have back probed the harness. it sounds like you may have a bad connector in the harness. try checking continuity on each circuit from the cruise switches to the speed control servo. the trailer light issue may or may not be associated.

you might try checking for a good ground at pin #4 on the speed control servo. then have someone press the brake pedal and you should have 12 volts at the same pin. if you have an automatic trans, the jumper is located above where the clutch pedal would be.

DOE

 

I have replaced the clockspring, at one point with the horn and cruise not working I wrongly thought that was surely it, but it wasnt. With everything apart I did test all the way from under the column to the servo, continuity was there. I can watch the switches do their thing with the different resistances at the servo end of the harness. I can see the bpp giving 12v until the pedal is pressed at the servo end of the harness. I can see 0ohm resistance from the brake pressure switch from the master cylendar at the servo end of the harness.

I've been through several diag test sheets and the only one I've found so far off is one asks for the voltage across #4 and #10 like all the others, but it also asks for the resistance. Voltage is fine but resistance is 2x the 20ohm limit. It then sends you to the brake position switch which checks out fine, then to check the clutch position switch or jumper, I havent located the jumper yet.

The trailer running lights are a similar deal, I can feel the relay functioning, fuse is ok, no juice at the end of the harness. Something somewhere is off.

Horn, I haven't made any progress there yet either, can hear the relay clicking also but no joy.

Only fuse that is open is the one for the heated seats, haven't pulled that open to look for burnt out wire yet which I guess is common.

Thanks for your time. I should get some more head banging against the wall today and I'll update.

 

good luck

DOE

 

wait, what? you have 12v at #4 on the servo end of the harness without pressing the brake pedal? it should be grounded until the brake pedal is pressed, then it should have 12v. are you checking this with the servo unplugged?

No sorry, thats the brake pressure switch behavior. Your right and I double checked, its behaving correctly

if you have continuity from pin #4 to ground, the jumper should be fine.

That would seem to make sense, but this one check specifically says it should be 20ohm or less resistance. The only thing I can find at all out of spec. Continuity is there and voltage looks good.

have you pulled this relay out to check the connections for corrosion? and or a continuity test? it could be clicking but not making the connection inside.

Pulled it and it looks nice and clean. I also undid the fuse block and tipped it up to look into the end, no mouse nests etc inside under the fuse block either.

well that says the circuit from the horn button is good. time to investigate the secondary side.

Today I can't hear the horn relay... I had been laying under it and hit the panic button in my pocket and heard it going click click click and thought that was one good thing about the horn not working. I have seen mention that the horn relay was integrated to the fuse box not one that plugs in, but I haven't put any effort into the horn besides hoping the clockspring fixed it.

are you testing your fuses with a test light or just a visual check? it is possible for them to look ok but still be nonfunctional.

I have a little tester with a light on it, I've tried with the fuse in the block as well as out of the block, and I replaced a couple just to be double sure.

I also today noticed the same behavior with the truck and the X, the brake pressure switch does very little to the voltage when the brake is pressed.

I can't figure out what the on switch does for the cruise controls. I get no voltage or resistance changes between pin 5 and 6 with the on button. I get all the expected resistance with the rest:

off 0
set 680
coast 121
res 2k

but looking at the schematic it looks like on doesn't complete the circuit between pin 5 and 6 but rather connects pin5 to the horn relay... Neither the X or the truck show any voltage or ohm changes when pressing "on", but the truck works...

hrm... horn doesn't work... on button connected to horn circuit somehow... cruise doesn't work... hrm... I can't figure out how the "on" should work though, and the behavior doesn't seem any different between the vehicles...

 

The horn and cruise have never worked for me, so the horn relay maybe not clicking anymore wouldn't necessarily be a candidate for "what changed", and I have made no changes other than the clockspring. Maybe I have a new problem with the horn.

 

ok the horn relay is just a normal relay, wonder where I got that integrated idea...

 

Ahem... !#$!#$

So the horn was the thing.

I had checked all the fuses several times. They were still all good.

I couldn't get the horn relay to click. Got to thinking, it was probably the lights clicking not the horn relay when I was under it and hit the panic button.

So I pulled the relay, tested ok, was clean. Checked for the constant power to the relay, none. So lets check for power at the fuse... at the fuse.... the fuse.... no fuse.

All the fuses were good, but not all the fuses were present... I am trying to figure out why someone would have done this on purpose. I took it for a drive, horn works, cruise works, didn't catch fire, didn't blow the fuse...

So again, assumptions bite me. Should have specifically checked the specific fuse, not just say "they are all good" and assumed "all" was all.

So now I have the trailer running lights left, and when its really cold it wont idle so I figure I need a new idle control valve which should be easy enough.

Progress, long overdue progress.

Thanks so much for helping.

 

Previous owner has horn mysteriously go
off at night. Removed fuse??

 

They had a remote start security thing on top of the ford remote entry and security module. Left lots of wires behind and the horn/siren thing. Maybe they had it such that the horn played tunes through the siren in dukes of hazard style.... Seems odd you would go without the cruise though even for fancy horn music. I guess I'll just keep an eye on it and see. Hasn't burst into flames yet.

I now find that the relay for the trailer running lights is ok, will switch as expected, but there is no power for it to switch. It clicks and connects the big terminals, but no power present.

But the list is getting shorter.

 

good news! so, the power for the trailer lights comes through fuse #4 in the battery junction box under the hood, it should be 20 amps. from the fuse block to the relay is a dark green with yellow wire and from the relay to the trailer plug is brown with white. should be a cake walk to figure this one out.

DOE