How to: END ALL 98-01 REAR WIPER PROBLEMS!

[CDW6212R]

I can't take all the credit for this one. Just wanted to take a minute to thank all you fine gentlemen who made this possible. It was Willcall's original post that inspired me to want to do this. Without his idea and research I think I would still probably be lacking a rear wiper. Also jcevans2 pushed me to acquire the 03 diagrams and really dig into the wiring issues. It is because of these members( and anyone else I may have forgotten ) willingness to share their ideas that mods like this are possible. It is a very cool mod and it works great, but it is a collaborative effort. Thanks to all those who made this mod possible.

Thank you Al.

I just got back onto the forum, and this was one of the threads I've wanted to revisit. I still haven't gotten to do my hatch glass, I bought it and the hatch wiring years ago.

The work you and the others have done makes this a reasonable project for anyone. I will get to doing mine this Spring. I could use a new hatch too, so I'll be looking for a whole red hatch, and the 02-05 Sport interior trim panel.

 

[mic98xlt]

Thank you Al.

I just got back onto the forum, and this was one of the threads I've wanted to revisit. I still haven't gotten to do my hatch glass, I bought it and the hatch wiring years ago.

The work you and the others have done makes this a reasonable project for anyone. I will get to doing mine this Spring. I could use a new hatch too, so I'll be looking for a whole red hatch, and the 02-05 Sport interior trim panel.

Great to hear from you again Don Al and others did indeed go out of his way to ensure this is a "reasonable project for anyone."

 

[albi1cnobi1]

Thank you Al.

I just got back onto the forum, and this was one of the threads I've wanted to revisit. I still haven't gotten to do my hatch glass, I bought it and the hatch wiring years ago.

The work you and the others have done makes this a reasonable project for anyone. I will get to doing mine this Spring. I could use a new hatch too, so I'll be looking for a whole red hatch, and the 02-05 Sport interior trim panel.

Great to hear from you again Don Al and others did indeed go out of his way to ensure this is a "reasonable project for anyone."

Thanks, Don. Haven't seen you around for a while. And mic98xlt, I appreciate that. I love a challenge. My background is in electronics and I don't get to use it enough. I'm glad it worked out and takes some of the guess work out of the mod.

 

[jcevans2]

Sincerest apologies

Hey jc. I'm looking for an 03 sport glass and wiper right now. I was looking at your posts, and I also think you're on the right track. I have a background in electronics, and your theory on the different wiper systems and how they work is pretty spot on. As soon as I get my hands on the window and wiper combo I'll let you know how it works out. I didn't have the 03 diagrams until the other day and after comparing them with the one for my 99 I think it should work.

I have to apologize for not responding much, much sooner. I have been wanting to get back to this thread but... life? Brutal winter, work, family, etc.

I lost access to the server where I posted my diagrams. That's why they disappeared from the thread and I had a computer malfunction and couldn't access my copies. I had used some photo editing to show a before and after version of the circuit diagrams with notes. When I can recover them, I will post them on a photo sharing site so we can compare. I should have done that from the beginning.

Thank you for looking into this and taking on the challenge of solving this problem.

 

[jcevans2]

I'll try to break it down a little more for you. Simply put, the 98-01 wiper motor circuit uses 2 relays and 4 wires to run the motor. The 03 circuit uses 1 relay and 3 wires to run the motor. In order to adapt the earlier truck wiring to run the 03 wiper motor you have to eliminate the un-needed relay. To do this you need to remove the "wiper down" relay(relay location #8 in the battery dist. box) and put a jumper in between pins #3 and #5 . This basically fools the 03 wiper motor and the GEM module into thinking all is well. Since you only need 3 of the wires and they're different colors on the different year truck and glass you need to figure out where they go. You can start off with the violet/yellow wire that fed the old motor. That wire won't be used now. It used to be for the GEM to know when the wiper was turned off so it could "park" the wiper down off the glass. The new wiper doesn't park like that so that wire isn't needed. 2 of the other 3 wires have basically the same function on both years, they're just different colors. The black wire is the ground on both so just splice black to black. The white/orange wire from the truck harness gets spliced to the violet/yellow of the new motor and the black/light blue wire from the truck harness gets spliced to the brown/white wire of the new motor. Thats pretty much it in a long rambling nutshell. If you do this and have any questions post em up, I'm sure we can help you out.

Sometimes when I try to explain something I make it more complicated than it should be. This is perfect.

 

[jcevans2]

You just put a small jumper wire with spade terminals on each end into the empty slots where the relay was plugged in.(in slots 3 and 5) If it's not dark out when I get home I'll take some pics and post them up, otherwise I'll get them in the morning. No problem, glad to help.

I got a relay at the junkyard when looking for other parts. I made a jumper block by cutting off the three appropriate blades with a small rotary tool and made sure the two remaining blades had continuity through the internal switching mechanism. The plastic case is easy enough to pry open. It makes for easy removal and installation in the relay slot of the junction box. You can easily label it with a sticker or a paint marker as a modification. I haven't used it because I have not attempted the wiper motor/rear glass swap (yet).


Jumper block made from old relay(left) and old relay with case removed (right)

I also took a photo of the junction box with my camera phone and copied it to my computer. I put text box labels on the photo on top of the various components (relays, fuses, etc.). I copied the edited photo back to my phone. When necessary, I pull out the phone and photos instead of flipping through the owner or repair manual. Pictures (annotated when necessary) of things like the engine firing order, spark plug wire routing, the service tag on the differential, the label on the inside of the driver's door, and labels on computer control boxes come in handy when you need to research a problem or search for parts.

 

[albi1cnobi1]

Hey JC. Good to hear from you again. I agree, brutal winter. Especially up here in the northeast. The mod is working great, no issues at all. It's really nice having a rear wiper again. I removed my old one a while back and installed a rear view camera in the spot where the wiper arm used to come through, so I kind of had to figure something out. lol!

 

[jcevans2]

Hey JC. Good to hear from you again. I agree, brutal winter. Especially up here in the northeast. The mod is working great, no issues at all. It's really nice having a rear wiper again. I removed my old one a while back and installed a rear view camera in the spot where the wiper arm used to come through, so I kind of had to figure something out. lol!

I reposted my original diagrams way back on post #22 and a pic of my jumper block on post #66.

 

[CDW6212R]

Thanks for the thread updating. I was thinking of my hatch this week, I've been hinting for an 02/03 assembly to replace my lightly rusted 98 thing. I'd like to find one to avoid having to fill the old wiper holes.

Did the latest modification of this make the wiper swipe just once at a time, or does it still go twice per?

 

[jcevans2]

I have an idea for the little twitch when the wiper is turned off. The GEM for the 99 is looking for a ground signal on the violet/yellow wire when the wiper is turned off. I'm thinking that in the absence of that ground the GEM is trying to "un-park" the wiper when the power is removed. Since this motor doesn't have to park it's just jumping up a bit from the GEM signal. When the wiper down relay was removed and jumpered the ability of the GEM to park the wiper was removed. When the jumper was installed it puts +12v on the black/lt blue wire and with no down signal the motor twitches up briefly. Like I said before the twitch is very slight and probably wouldn't bother most people, but if I can fix it all the better. I'm going to try a couple of things and report back. I'll let you know.

You may be right. If you look at my diagrams on post #22 , you will see the violet/yellow wire from the GEM park sense goes through the old motor and then to ground. On the modified diagram, I just have the violet/yellow wire hanging and labeled "no longer used". Maybe it should be connected to ground (black wire). The GEM will think it has told the new motor to park and the circuit will be complete but it doesn't actually go through the motor; only to ground. The new motor parks itself internally. That's why it only has three wires instead of four.

 

[jcevans2]

Here is a simplified version without all the irrelevant stuff.



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[albi1cnobi1]

Thanks for the thread updating.

Did the latest modification of this make the wiper swipe just once at a time, or does it still go twice per?

Here is a simplified version without all the irrelevant stuff.



==============================================

Hey Don. No, it still wipes twice per cycle. But I've gotten used to that, I don't even notice it anymore.

JC, I haven't had a chance to try the ground on the other wire yet. Life got in the way. It should work, and I will post results when I finally get to try it. Sorry for the late reply, I was camping and off the grid for a bit.

 

[jcevans2]

Hey Don. No, it still wipes twice per cycle. But I've gotten used to that, I don't even notice it anymore.

JC, I haven't had a chance to try the ground on the other wire yet. Life got in the way. It should work, and I will post results when I finally get to try it. Sorry for the late reply, I was camping and off the grid for a bit.

There is something that has been bugging me. We know for a fact the generic electronic module (GEM) from the 1999 model alternates the direction of current "pulses" through its wiper motor to create the up and down cycle. But I don't know exactly how the GEM from the 2002/2003 model controls its wiper motor. I think it allows electrical current to flow through the motor in only one direction. So...

Case 1:
Is the current continuous and creating both up and down action (through some kind of internal gearing perhaps)? If so, then connecting the motor to the "pulsed" current of a 1999 GEM may be the cause of the unusual wipe cycle. The pulses would basically be turning the motor on for two wipes and off/park, on for two wipes and off/park, repeat.

Case 2:
Is the current "pulsed" and creating an up action during a pulse and a down/park action after the pulse? If so, then connecting the motor to the "pulsed" current of a 1999 GEM doesn't really operate the motor differently. Maybe the timing of the 1999 GEM is the cause of the unusual wipe cycle.

 

[albi1cnobi1]

Time to resurrect this thread. I haven't really done any more work on the rear wiper since our last posts. It's amazing how lazy we can get when everything is working correctly. Fast forward to a few days ago, when my rear wiper stopped working. Now I have to dig into it. I started checking for all the necessary voltages at the motor plug and found that the constant 12v signal was there but the pulsed signal was not. I checked everything, the switch, the relay, all was as it should be. I'm thinking some part of the mod wiring has failed. While standing there scratching my head, I was staring at the wiring hanging off of the OPEN rear window wondering where my pulsed signal was. Then the "You're a moron" moment happened. Opening the rear window disables the wiper. Believe me, it's only obvious when you're not over thinking everything! Now, after closing the window and checking again from the inside all the voltages are there, both the constant and the pulse. Easy-peasy, bad motor. Now for some reason these motors are about $20 more than the one for the 02 and up rear motor and they have $25 core charge so off to scour the internet for one at a jy. Found one, got it, installed it, and nothing. WTF! So off to the bench for some testing. Turns out the new(used) motor is bad. Frozen solid. Can't catch a break. So I start into the original motor. There is a diode wired in line with the motor so that when the internal park function operates the 12v doesn't backfeed to the constant 12v feed. Well when I tested the diode it was bad. A quick trip to radio shack and my wiper is back in business. But while I was doing some tests on the bench, I did figure out why the wiper sweeps twice each time. The pulse from the pre 02 GEM is longer than the one from the 02-03 GEM. The pulse stops just a hair after the first sweep ends, so it starts another sweep. So now I'm intrigued. Is there a way to shorten the GEM's pulse? Figured I would throw that out there and get some more opinions. What do you guys think?

 

[CDW6212R]

Good work, and thanks. It all helps, and your repair sounds like many of mine have gone.

I've been planning to hunt a mid-2002 to 2003 hatch for my Mercury, and lately a new 98-01 truck to begin with. Gotta keep plugging along, we will get it done eventually.

 

[Mike's brother]

Gents ... this is amanzing work, and above-and-beyond sharing. I'm adding this to the "if I bump into it at the JY" list for a future weekend project. Thanks!

I vote sticky on this one. :exp:

 

[albi1cnobi1]

There is something that has been bugging me. We know for a fact the generic electronic module (GEM) from the 1999 model alternates the direction of current "pulses" through its wiper motor to create the up and down cycle. But I don't know exactly how the GEM from the 2002/2003 model controls its wiper motor. I think it allows electrical current to flow through the motor in only one direction. So...

Case 1:
Is the current continuous and creating both up and down action (through some kind of internal gearing perhaps)? If so, then connecting the motor to the "pulsed" current of a 1999 GEM may be the cause of the unusual wipe cycle. The pulses would basically be turning the motor on for two wipes and off/park, on for two wipes and off/park, repeat.

This would be the case if the wiper circuit were left un-modified. But since we have removed the wiper down relay, we have in fact, simulated the 03 wiper circuit. So this isn't the cause.

Case 2:
Is the current "pulsed" and creating an up action during a pulse and a down/park action after the pulse? If so, then connecting the motor to the "pulsed" current of a 1999 GEM doesn't really operate the motor differently. Maybe the timing of the 1999 GEM is the cause of the unusual wipe cycle.

Bingo. jcevans2 has hit the nail on the head here. That is exactly what is happening. The only difference is the duration of the pulse. The 03 motor only needs a very short pulse(in the range of .5 to 1 sec) but the pulse from the 1999 GEM is a bit longer than that. So the 03 motor is reaching the end of it's first sweep before the pulse ends, so it starts another.

[/COLOR]
If the pulse could be shortened, by perhaps about half, this would stop the second sweep. Like I've said before, the double sweep really doesn't bother me. I don't even notice it. But maybe I'll dive into this when I get some time, just to see if I can beat it. lol!

 

[mic98xlt]

Still loving this thread, Guys! Shorting the pulse I believe is indeed the answer! I noticed at the JY, some later models Ford Escapes and Mercury Mariners have the same identical wiper motor mounted on the rear glass as those on the '03 Sports. The rear window glass (Escape and Mariners) is different (shaped and size) from the Sports.

 

[albi1cnobi1]

O.K. quick update. I hadn't put the lift gate trim panel back on yet so I thought I would play around with the wiper circuit. I tried to figure out the little "twitch" in the wiper after the wiper switch is turned off. First thing I did was apply jcevans2's theory and ground the old park sense wire(vt/yel). That didn't stop the twitch, however it did happen quicker! There was no delay after turning off the wiper, it happened right away. I also tried using a relay on the park sense wire so that it was only grounded when the wiper was turned off. No difference there either. Another thing I noticed is that on the 98-01 wiper relay when the relay releases it goes to ground, but the 02-03 wiring does not. So I modified an old relay by removing the terminal that connects to ground. This had no effect either. So back to the drawing board on this issue. Need to put some more thought into this one and see if we can figure it out.

 

[albi1cnobi1]

A small side note, not related to the wiper itself. Since the washer nozzle on the 98-01 is on the wiper arm, when the 03 wiper is installed you lose the washer on the rear window. I'm in the process of adding back the rear washer nozzle on my truck. I'm going to put it in the same place as on the 03, above the window on the hatch. I'll post some pics as I make any progress.