98 Explorer Multifunction Switch

[trw999]

This one has me scratching my head!

My faithful 98 Explorer, owned 12 years here in the UK, just failed it's annual MoT test due to inoperable indicators and hazard switch. Oddly they had worked fine when I drove the car into the shop!

First off, it was not a fuse. Secondly, I thought the relay may be shot. Replaced with new one, but that did not cure my problem. So I popped the old relay back in and will keep the new one as a spare.

Looking on the forum here I diagnosed that the multifunction switch was my culprit. So I bought a new (Chinese) one for my model and fitted it. Yipee, the indicators and hazard work, as does the headlight dip. However, here is the perplexing thing, the windscreen wipers are permanently on. The only way to switch 'em off is to pull the fuse.

Suspecting the Chinese could have mis-wired the new switch, I called up my friendly Explorer breakers yard and ordered a working second-hand multifunction switch. That was more expensive than the Chinese newby, weirdly. So I fitted this version and still have a problem with the wipers; rest of the switch works fine.

So, we know its not the fuse, its not the relay, the wipers worked fine beforehand so the wiring in the car would seem fine. It all points back to the multifunction switch. First thought about that is that perhaps during 98 they made subtle changes to the switch and I have had two versions of the wrong one. Second thought is I wonder if there is a way to change the wiring in the switch that would help. I'm pretty much at the end of my capability in this department so would welcome thoughts and suggestions, please.

Tim

 

[BrooklynBay]

Do you have a schematic diagram of the circuit? You could check both switches with a continuity tester to see if they are turning on & off or just remaining in the on position. Check the wiring in the steering column for damage. Maybe some insulation got pierced, and grounded to the metal frame.

 

[J_C]

First, I was amazed how easy it was to refurb my '98 multi-function switch. Take 5 x T10 screws out, scrub it with brasso metal polish (any petroleum based polish OR use a slightly gasoline dampened rag to scrub the old hardened grease off first) or fine sandpaper, till the copper is shiny, wipe it clean, then put a coat of silicone dielectric grease on the contacts (optional).

Looking at the wiring diagram, the only thing that would make sense to me for why you have two different MFS causing the wipers to stay on is if the pink/yellow wire to it were shorting to ground, and I'm not even sure about that. Do the wipers come on when the MFS isn't even connected?

The wiring diagram for that is attached.

 

[trw999]

Thanks for your replies.

The wipers do not operate when the MFS is disconnected, nope. Neither can I find any shorting wires.

I rather think the problem lies in the wiper motor itself. Perhaps the pulse circuit board attached to the motor has had it? That is what I am exploring now.

Tim

 

[J_C]

I doubt that's it. A problem with the pulse board in them could keep them from working but wouldn't explain them staying on because there should be no power to the wipers when they shouldn't be on.

They're turned on by the Wiper Run Relay activating, by 12V going through its coil. That relay's coil input is pin 1, is live 12V with the ignition in accessory or run, and that relay's coil pin 2 is grounded by the GEM module, at the (wiper speed) interval determined by it sensing an analog signal (resistance based) coming from the multi-function switch.

The GEM senses this by putting a voltage through the MFS on a pink/yellow wire and the gray/red wire. If both read (nearly) the same voltage then I suspect there is a wire short or the MFS is bad. If only one reads a voltage and the wipers still run, I would suspect a GEM module problem.

I could be wrong, the only time I recall someone here have a GEM module failure affecting the wipers was loss of the delayed wipe modes, that the wipers otherwise still turned on and off as they should.

 

[trw999]

Having been beaten by this I called on Colin, my friendly mechanic. He checked out the problem and concluded that the multi function switches I had were defective/incorrect. So I'm now on the hunt for the definitively right one.

My Explorer is a Model Year 1998, but with a build date of 25 Sep 97. First registered in Feb 98, so it must have taken a while to ship across the pond to us here! I mention this because so far I have found 19 different part nos for 98 Explorers - I kid you not!

So assuming the Ford part to be the one, I have narrowed that down to SW5581 (13K359), or Ford Motorcraft parts SP251 or SW5581 or Rock Auto parts F5TZ 13K359B, F77Z 13K359AA, F87Z 13K359AA, 5T 13K359BAW or YL5Z 13K359BAA (this last being the same as the SW5581).

So does anyone have knowledge of or access to the parts lists to be able to decipher which one of the above is which and thus, which switch I need to order?!

Tim

 

[J_C]

^ While I don't know it to be "necessarily" true, I would suspect that all MFS that look alike and have the same connectors, should work.

My '98's factory part # for the MFS, is F77B13K359AA. I got it right off the switch itself when I took it out to clean it... but I was cleaning it to fix the turn signal(s), don't know if the switch mechanism for the wipers can be taken apart to clean.

 

[trw999]

Thanks.

I wonder what the difference is between your F77B 13K359AA and the Rock Auto F77Z 13K359AA? We could be at this a long time!

Tim

 

[J_C]

I suppose I had the impression that "359" was the important #s and everything else had to do with a revision, supplier, factory run, or something like that. AFAIK "B" could mean original equipment and "Z" means sold as spares.

My vague recollection is that people have bought these for their 2nd gens off various places like eBay and it didn't matter if the part # exactly matched.

 

[trw999]

Okay, managed to get this sorted, almost accidentally.

First off, I can now confirm that the part no for the MFS is 13K359 and all else is superfluous.

Secondly, with nothing to lose, I decided to open out one of my three MFS to have a look and give it a clean. Thanks J_C! The original to my car MFS was really gunky inside and I suspect was the cause of the problem in the first place. So I used it as a learning process, then tackled number 2 MFS, which I had got from a breakers. It too was quite gunky, but I soon had it cleaned up and back in one piece.

After all the shenanigans I had lost the will to live, so left the whole sack of work and went away for several days. When I decided to tackle things again, I thought I'd just try my newly cleaned up MFS. And it all worked! As it should.

So thank you all for your suggestions and assistance, but big thanks J_C - top man!