I have a 1999 SD diesel, and just recently my wipers will not stop running after they are turned on! When I flip them on to any position, they will run on "low" but not intermittent, and when I go to turn them off and twist the switch to the "off" position, they continue to run indefinetly, even after the truck is turned off and the key is removed. When this happens, the only way I can get them to stop is by pushing down on the actual wiper arm itself until they catch and stop. I have a suspicion that it is the relay or switch itself gone bad, but am not for sure and could use any and all help from someone who may have been through this before! The wiper motor appears to be fine, but I cannot figure out how to narrow down the exact problem. I thank you in advance for all the help!

~Elkman

 

There are three controls for the wipers, which work together to make them run, park, and intermittent.

The multifunction (turn signal) switch sends a signal to the GEM module which tells it what function to select. The GEM then controls relays in the underhood junction box to make the wiper motor run (or park) in the selected manner.

Look in your owners manual for the W/S/W run/park relay and the W/S/W high low relay. Try unplugging them one at a time and replacing each with a known good relay. If the relays do not fix the problem, then you need to troubleshoot the switch and GEM.

You will have to take the cover off the steering column between the instrument panel and the steering wheel, then get the wipers to start running. If they quit when you unplug the multifunction switch connector (rectangular-shaped, at the base of the turn signal lever) then you need to test the switch, or try a known good switch.

If the switch does not fix the problem, then there may be a contact sticking within the GEM. This is a real problem, since I have not found a source that repairs the GEM, and Ford wants an arm and a leg for a new one, and any GEM installed in your truck has to be reprogrammed to match your truck by a dealer or someone with a very advanced scanner/programmer.

Try removing both battery ground terminals for a few minutes, then reconnect and see if that helps the problem. If it doesn't, then try switching relays and report back.

 

Also check for water on top of the fuse panel. The earlier trucks mounted the GEM on the fuse panel, then some of the windshields started leaking. The water shorted out the GEMs and caused general electrical weirdness.

 

The Gem could be getting wet as reax states but unless there have been changes in later model years the gem does not have to be reprogrammed, you have to buy one that is for your truck but it is a replace and drive item, dealer not needed other to get the part. If you truck is a 2wd I may have a new gem for your truck. I'm not sure if they are different from gas to diesel.

 

My truck has a manual shift transfer case, and the GEM has a sticker on it that says 2WD. It may be that the 4WD GEM is needed only for the electric shift transfer case.

 

Couldnt help but to tell you a story of a friends station wagon,

it was an old hunk of junk, " back when we were kids "

every time you would floor it, the wipers would come on......

never did try to fix it, it was too funny

 

had a VERY similar problem with a Mercury cougar i had..

turned out to be a rust problem inside the wiper motor itself.

course the SD is a completly different animal but its possible u have moisture getting inside the wiper motor and rotting it...

 

i am intirested to hear more about this rust problem....the truck spends a lot of the winder out in the snow and cold weather, so this could be the culprit. I have been playing with it all morning, and so far the relays are working properly, but I cannot get the multifunction switch unplugged because of how tight the clearances are under the steering column. How did you come to the conclusion that it was rust? It doesnt seem like an obvious thing to check for.

 

The early Super Dutys had an issue with the windshield leaking and water dripping onto the gem and fuse box. The gem is bolted to the backside of the box, see if you can tell if it's been getting wet. The cure is to have the windshield taken out and resealed, evidently must have had a newbie putting windshield's in or a bad seal.

 

Switch went out on my F750 this past winter, was doing basically the same thing.

Thought they were parked until smoke started coming out of the dash. Ended up with a new switch and motor.

My bet is on the switch.

As for weird occurences, same truck, the interior light comes on when you depress the brake pedal. Still haven't figured that one out yet.

 

basicly with my wiper issue when we took the motor out to replace brushs (which we thought was the issue) the inside of the motor fell apart... was completly ruineds internaly from corrosion..

i was suprized it had worked as long as it did when i saw what came out of the wiper motor shell... basicly a armature and a BIG pile of orange debris.. hahaahah