How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask AMEDEE Your Own Question
Category: Ford
Satisfied Customers: 26083
Experience:  ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
Type Your Ford Question Here...
AMEDEE is online now
A new question is answered every 9 seconds

97 F150: wipers wont work - checked the mfs..relays..few seconds

Customer Question

'97 F150 - Wipers won't work - checked the MFS - good resistance readings everywhere, swithced the relays around, bought a used motor - installed still nothing. Took the GEM out today - no signs of water or moisture - however door chime came on for a few seconds then went out - none of the chimes are working. Do you think I have a bad GEM or what. How can I double check the motor without taking it back out?
Submitted: 5 years ago.
Category: Ford
Expert:  AMEDEE replied 5 years ago.

Are there any codes in the computer?

Have you checked power and ground to the wiper motor?
Customer: replied 5 years ago.

I checked the 5 pin connector that connects to the wiper motor:


Looking at the connector with the clip on top (pins 1 -5, left to right) - I measured with the negative meter lead to the ground terminal on the battery:


I got:


1 - 5.4V, 2 - 12V, 3 - 0V, 4 - 5.4V, 5 - 0V


These readings were the same whether the MFS was in the 'off', 'lo', 'hi' - or intermittent. I was assuming there would be a change from off to on.


I don't have a code reader or anything, was just looking for water in the gem/fuse box.

Expert:  AMEDEE replied 5 years ago.
Does the cruise control work?

What about the dome lights?
Customer: replied 5 years ago.

Cruise control works - no problem.


Took fuse out for dome light a few months ago cuz it would take forever to shut off. Assumed it was the switch in the door.


Do the readings for the motor sound right?

Expert:  AMEDEE replied 5 years ago.
The white/black wire should have battery voltage. I believe this is pin 2

PIn 3 is ground and pin 5 (white wire) should have power on high.
Customer: replied 5 years ago.
so, If I don't have 12V across white & and pin 3 with the wiper switch on high - and knowing the MFS is good, do you think it's the GEM - what else should I try??
Expert:  AMEDEE replied 5 years ago.
If you do not have power on the white/black wire on pin 2, then check the 30 amp fuse number 11 in the junction box fuse relay panel.
Customer: replied 5 years ago.

I do have 12V on black/white all the time. The 30A fuse is good, first thing I checked.


So the pin #s I gave you before: 1-Blue, 2-Blk/Wht, 3-Blk, 4-Wht, 5-Blue/Orange. I always have 12V on pin2 (Blk/Wht). The readings I gave before: I have 5.4V on Pin 4 (Wht) no matter what position the switch is in with the key turned on. I also have 5.4V on pin 1 (blue) - no matter what swithc position with the key on. Can I put power from the battery to black (-) and white (-) to dbl chk the motor. Or will this cause problems....



Expert:  AMEDEE replied 5 years ago.
Yeah.. you do not want to do that.. the black is solid ground.. same as battery ground given that it has a good ground or a good connection to ground.
Customer: replied 5 years ago.

There are three identical relays in the fuse box (engine compartment) - wipers - hi/lo, wipers - run/park, washer pump. Positions 1,2,3. I switched these around to see if I had a bad relay - if one of them is gone will it cause nothing in the wiper system to work? Is there a way to check these relays (they don't click like the larger ones)

Expert:  AMEDEE replied 5 years ago.
You can ohm these relays out.. 70 to 90 ohms is about right.

I would check both of the high and low speed relay for a ground from the GEM with the switch in the high and then low position with the key on./

Also, be sure that both of these relays have two powers with the key on.
Customer: replied 5 years ago.

Ohm'd all three relays earlier - all about 90 Ohmk, +/- 1 Ohm. So I figured they were good.


The hi/lo relay is one relay only. I'll wrap wire around the relay posts so I can check to see if there are two powers on each with the key on.


The GEM is hard to get to, I don't have a detailed wiring diagram. Don't know how to check for ground to the relay..

Expert:  AMEDEE replied 5 years ago.
YES.. just clip the alligator side of the test light to battery power and then touch the tip of the test light to the cavity in each relay pin 2. The test light should blink or flicker when the GEM pulses the relay to activate the wiper.
Customer: replied 5 years ago.

I'm not using a test light, but I did the same thing with a fluke multimeter, hooked one lead to battery power - other lead to pin 2 receptacle for the hi/lo wiper relay. Voltage did not change at all - it remained like 0.07 and didn't flicker.

Expert:  AMEDEE replied 5 years ago.
Ok.. I am not sure if you will get a reading on your meter. If you are able to get a reading but the GEM is not sending out a signal then you have an issue with the GEM. It could be bad or missing an input preventing the wipers from working.
Customer: replied 5 years ago.

Input is from the MFS which is good. Unless there is a bad connection somewhere.


I checked the relays - there are two powers on all with the key on as there should be.


If you are able to get a reading but the GEM is not sending out a signal then you have an issue with the GEM.


Don't quite get what your saying here. I double checked (had to make a wire to fit into relay cavity pin 2. I have 0V there with the switch in hi and lo. So it seems to me that there is no output from the GEM to the relay. Relays are good.


How can I double check the motor??

Expert:  AMEDEE replied 5 years ago.

Sorry for the delay!

I would agree! It sounds like the GEM is going to be the root cause here or at least the GEM is not sending a signal to the wiper relays for some reason that we yet need to determine.

I meant to say that if you run the test right but still do not get a signal from the GEM, then the issue is going to be something with the GEM.

To check the wiper motor, all you have to do is check the inputs. Or another way is supply power and ground to the motor and it should work.

Again, the black wire is ground, the white/black wire should have power and the white wire or DB/O wire should have power depending on where the Hi/low relay is set.

If you are not getting power on all the two power wires, you can manually just power these up and see if the wiper motor works.

Let me know!
Customer: replied 5 years ago.


the link above is the one I found for MFS test. All the resistance values were very close to what the chart shows. In some cases they weren't exact but very close. I tested this with the MFS out. I'd have to take the connectors back off the GEM and check the resistance values on the same wires at the GEM plug to ensure the signals are getting from the switch to the actual GEM. Could be one of the connectors, either on the MFS or the GEM - when I had it apart all the pins looked clean at the GEM connectors (two bolt on ones) and on the MFS connectors. I could not get the small grey connector out of the side of the GEM itself - these are the inputs I'm assuming? The connector did not want to come out, I did not want to break it. I opened up the GEM and there were no signs of moisture at all, no rust.


Having checked all fuses and everything again - installing all fuses where they should be. I took apart the negative post of the battery and cleaned up the clamp (very corroded) and checked the ground wire hookups to the battery, wires do not to be corroded or anything. From the wiper motor connector I confirmed there was good ground (closed circuit from negative post to black wire on connector).


With all fuses in and good, my symptoms still are:

No wipers - hence no washer pump

No door / key in ignition / light chimes

No Dome light


Everything else on the vehicle works fine, no issues.


Physically, it's very difficult to put power to the motor connection because of the connector socket. I need to put power on blk/wht, and wht - and at the same time ground black - which is in between the two powers. I have alligator clips - I'll try it if I can insulate between the alligator clips somehow. If I took the whole assembly back out of the truck it would be easier - might have to.


I'm going to see if the Haynes manual has the wiring diagrams I need - it would save me from bothering you.


If the small grey connector on the side of the GEM carries the inputs - I'll check the values from the switch at that connector. If the inputs are getting there and I find that the motor is good, I'll know it's got to be the GEM. Do you agree.


If I put



Expert:  AMEDEE replied 5 years ago.

Sorry for the delay! I just stepped out with the family for a bit.

YES.. if ALL of the inputs check out ok to the GEM and the GEM is not responding, the GEM is at fault and will need to be replaced.
Customer: replied 5 years ago.

I removed the fuse box / GEM today. I was able to get the input plug / harness out of the side of the GEM this time. I traced the wire colors back to the MFS. I ohmd the MFS signals at the GEM female connector. I had to make wires again so that they would fit in the GEM input connector. I found the resistance values to be higher in some cases measured at this connector, however, they follow the same pattern for testing (ie. i3.3KOhm (on hi) to 100.3KOhm on the slowest intermittent setting). I assumed that the readings were higher because of the additional connectors, length of wires, and homemade pigtails I had to make to test.


I grabbed a test light while I was out too. Good ground at the wiper motor connector, good battery power (blk/wht) - no power at wht or db/o with the switch in any position. Removed the hi/lo relay for the wipers and repeated the test at pin 2. Pin 1 of the relay has 12V as it should - pin 2 has nothing with the switch on hi or lo - light doesn't flicker.


Since my dome light and door chimes are not working either, inputs to the GEM seem fine, relays have 2 powers, ground is good to motor, battery power blk/wht is good to the motor - it has to be the


I'm sure you've had a good laugh at me - the GEM is $400 (before programming and installation) - so I really wanted to make sure that I needed it. And that I wasn't missing something stupid like a bad connector or whatever.

Expert:  AMEDEE replied 5 years ago.
Sorry for the delay!

Based on the information you have provided me with, it really sounds like a bad GEM.

HOwever, you got to understand that this web site is for informational purposes only. It sounds like you are trying to hold me accountable for this diagnoses as I am not even there is front of your vehicle. Please remember I am just trying to help you.. but my hands are tied because I am not there testing your vehicle myself.

If I were you, I would check the inputs to the GEM. Check the powers and grounds. I can tell you what pins to check but cannot copy and paste any diagrams as it is against copy write laws to do so.
Customer: replied 5 years ago.
I am not trying to hold you accountable at all. I appreciate your help - once I went and grabbed a manual with the wiring diagrams it was simple. I use to do 24V control systems and PLCs, I should have known better than to trying to troubleshoot electrical over the phone/email without a wiring diagram!!! Honestly to start, I thought the system was much simpler - especially since it was a '97.

With the wiring diagram, I could then see why I needed two powers to manually test the motor - which I did and it worked fine. I then used the diagram and meter to determine what wires went to what receptacles in the pdb. I battery tested all the relays to here them click and see the power side continuity change.

MFS was good and inputs to GEM at GEM were good. Further to that I made a list of all the things that weren't working - everything the GEM outputs to. I now have a high tech control system consisting of two toggle switches on jumpers to the relays until my GEM arrives. For 400 - covered every possible fault. Thanks.
Expert:  AMEDEE replied 5 years ago.
NICE! That will do the trick! Pretty clever! I think you are definitely headed in the right direction!

Please let me know if you have any further questions!

I DO hope you found my Answer to be helpful regarding your vehicles condition. IF SO-please hit **ACCEPT** as you read this Answer, in order that I may receive credit for my time, thanks. BONUSES & Positive Feedback Most appreciated!
Please Note: I receive ZERO Credit until & unless you choose to ACCEPT my well thought-out Answer.