First time poster here. I worked on this for 2 weeks before I broke down and registered. I have read every post I can find and looked through hundreds of pages of wiring diagrams and pinpoint tests. I CANNOT get this problem fixed.


Here is what is going on....


2003 F250 4x4 RCLB XLT V10 Auto. ESOF, NO Keyless entry. I believe this to be a rare combination that does NOT have a GEM.


Out of the blue, wipers and washer are dead. Nothing. Nada. I can hear the relays on the wiper motor click for all functions. Everything else on the truck works just fine.




Things I have done so far.....


Scanned for codes.


3 different wiper motors (2 "new" Re-manned).


I performed all pinpoint tests per the service manual at wiper connector C125 and Multi Function switch connector C202b.


Bench tested the multi function switch.


Removed dash and instrument cluster to inspect every loom and connector.


Inspected all connectors and relays mounted on the drivers side inner fender.


REMOVED the fuse box (PJB) Inspected all connectors, fuses and relays.


Swapped all relays to different circuits.


Inspected all grounds.


Tested with different instrument cluster.




All circuits test exactly like they should except one. I am not convinced this is the problem but circuit 676 (pink/orange stripe) at pin3 of the C125 connector is showing 12-14 ohms with the key off. The testing procedure says that it should be less than 5.


I followed this circuit to connector C220c pin 13 on the instrument cluster. It measures 12-14 ohms at the back of C220c when it is plugged into the cluster. If I unplug connector C220c the circuit measures 0 ohms to ground. A continuity test from C125 pin3 to C220c pin 13 shows 0 ohms. I swapped in a different gauge cluster (identical part number and manufacture date) and had the same exact results.


Circuit 676 is labeled as a "logic ground"




Where do I go from here? I am a reasonably intelligent person and this problem is kicking my butt.


Any and all help/suggestions are greatly appreciated.


-Eli

 

Anyone? I am under the gun to get this fixed.

 

That does sound strange. You hear the relays click, so the control circuit is functioning at least that far. The relay uses a low amp circuit to switch a high amp one. Is there a way to measure on the output side of the relay to see if the hi-amp (power to the motor) is actually present?

I have not looked at the diagrams, but a lot of automotive circuits have the switching on the ground leg of the circuit. Might it be as simple (and hard to find!) as a poor ground?

Any way for you to scan and post the wiring diagrams? I think you need a minimum number of posts on the forum to post an image, so a link to a Photobucket page would be fine - just something so others can look at the diagrams, scratch their heads, and offer suggestions.

Good luck - electrical issues are such gremlins!

 

Thanks for the reply and the suggestions.


The relays are in a sealed unit that is part of the wiper motor. I have tried 3 different ones and they all do the same thing.


According to the testing procedures there is nothing left to test. I just don't know where to go from here.


-Eli

 

More information:


Circuit 65 (DG) runs to pin 5 on the C125 wiper motor connector. This is a heavier gauge wire that supplies constant voltage to run the wiper and washer motors.


The pinpoint tests say to test this circuit with C125 unplugged. It measures within spec when tested this way. (over 10V)


I just went out and measured the circuit at the back of the plug with it plugged IN to the wiper motor. It measures like it should until you try to activate the washer or wipers. When the signal is sent to run the motors the voltage on Circuit 65 drops to 0. When you switch the wipers back off it pops back up to over 10V.


I am about ready to set this truck on fire.


-Eli

 

Sounds like a partially broken wire

 

My old Army electronics instructors drilled two things into my head back in the old days: Always verify your grounds and always verify your supplies before doing anything else.

I see two things in your descriptions that are not consistent with the schematics:

1) C125-3 should always measure 0 ohms to ground all of the time. See cell 10-22 in the EVTM for details. The circuit should be C125-3 -> Splice S172 -> Connector C146-1 -> Splice S201 -> G300. G300 is located behind the driver's kick panel and is subject to corrosion. I'd do a visual exam there first. If nothing unusual is noted, I'd connect a heavy jumper directly from that ground stud back to the battery negative post so as to bypass any potentially open grounding straps between the cab and the chassis.

2) The Dark Green wire on C125-5 should be ALWAYS HOT regardless of anything else. Your reading suggests that either your meter's negative lead was connected to a point that had a high resistance to real ground or there is a high resistance in the feed circuit from F2.106 via the DG wire.

My suspicion is that you have a bad ground. A series of voltage drop tests from the battery negative post to the chassis and cab (G100, G300, etc) will likely show that there is a problem somewhere between G300 and the battery negative terminal.

Repeat this test with the battery disconnected or with the meter leads reversed and I'll wager you'll get different readings.

 

Thanks for the suggestions. I will go back and verify some things.


Couple of things to note here....


I have checked and loosened/re-tightened all grounds that I can find. Including G300. There is no corrosion on any of them. I will try jumping to the battery -.


C125 Pin 3 (circuit 676 PK/OG) reads 12-16 ohms at the C125 connector (plugged in and unplugged) and at both sides of C146. It also reads 12-16 ohms at the back of C220c (back of instrument cluster). If I unplug C220c it measures 0 ohms to ground at all the above points. I jumped this circuit straight to the firewall ground from right behind the C125 connector and had the same results.


C125 pin 5 (65 DG) is always hot until a relay is activated in the wiper motor. If I press the wash button on the multi function switch I hear the relay on the motor close and the voltage on C125-5 drops to 0. As soon as I release the button it jumps back up to 12V. The same thing happens if I select any of the wiper functions.


Everything else in the truck works as it should. I am heading back out to the shop after I finish my coffee and I will recheck some of your suggestions.


Thanks everyone for the help.


-Eli

 

I would track out C125 to find out where it is loosing voltage when the wipers try to start.

 

C125 pin 5 (65 DG) is supposed to be always hot regardless of anything else. It's a straight connection to the battery via the fuse. therefore, there's either a testing error or a high-resistance in the circuit across which the voltage is getting dropped when there's a current demand.

The cluster always pulls a little current, even when ignition power is off. When you unplug the cluster, that current drops to zero.

Since you have EE education this should be readily followable, think about how an ohmmeter works: It's a constant current source combined with a voltmeter. That is, the meter supplies a constant, known current through the circuit under test then measures the voltage "dropped" (or generated) across that resistance. A little internal math and a reading is presented in ohms.

My bet is that the resistance reading of 12-16 ohms will change significantly if you do either of two things: Reverse the meter leads (constant current will be flowing in opposite direction, either adding to or subtracting from the current drawn by the cluster) or disconnect the battery (removes all current flow from rest of vehicle).

One other thing came to mind regarding grounds. I recall reading about some unusual symptoms due to failed ground straps between the frame and the cab. Don't recall the details, but that's something to keep in mind.

 

This is one half of the possibilities. It's necessary to properly manage the positioning of both meter leads in order to get valid data.

Easy enough to check, though. Connect positive meter lead to battery positive terminal. Connect negative meter lead to C125-5 (Back probe connector). Turn on switch for wipers.

If that supply circuit is good, the reading should remain near zero volts. It it's bad, then the reading will show up to full battery voltage. In that case, continue half-splitting the remaining circuit to find the fault.

 

Ok. Here are the results...


Meter positive to battery positive. Meter negative to C125 pin 5 (DG) with C125 connected to the wiper motor.


Key in run position and the meter reads mV. Wipers on or washer pressed makes the meter jump to 12V.


This would leave me to believe that something is shorting the supply circuit to ground but only when a wiper function is called for. I also plugged in a new wiper motor that I have and retested with the same results.


What next?


-Eli

 

You need to work your way back to battery supply to find the point it does not change. My next check point would be at the fuse. It is not a short but a restive connection.

 

Ok. Understand. I would use this logic if the positive battery post test showed voltage at all times but it does not. It only does it if a function is selected on the multi function switch that closes a relay on the wiper motor. Is my thinking off here?


I tested both ground circuits C125--3 and C125-6 for voltage when the wipers are on. Tested with the positive lead inserted behind C125 plugged into the wiper motor and the negative lead wired directly to G300. No voltage detected on either ground when wipers are on.


Something else interesting that I stumbled on.... C125-3 (676) is the ground circuit that is measuring more resistance than it should. I left the meter hooked up to C125-3 (positive lead) and had the negative lead to G300. I left the truck for about 30 minutes and had the door shut and key out. When I came back the meter was down to .2 ohms. When I opened the door the resistance jumped back up to 12-16 ohms. I repeated this test but this time I did not open the door. I reached through the window and turned the key on. Same result.


-Eli

 

Parasitic load of the car. The way I would test this is with a test lamp to ground (non LED), wiper switch on, key on start at the fuse if it lights on both sides fuse good, next at the wiper motor if it lights there you have a bad ground if not backup on the supply wire until it does light. I have seen factory crimps go bad so you may need to probe thru the insulation on the wire.