Nashville TJ's Build - Continued

NashvilleTJ said:
The old rig would pull 65 through there, but not 80. We’ll see how 300 extra foot pounds and 4 extra gears does.
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Mine could set the cruise at the speed limit and won’t drop out if 10th unless someone else slows it down. Your trailer and jeep may weigh a bit more though.
 
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Well,,,,, &%^#!

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Back to the drawing board.

Anyone have any advice on what to diagnose next? I need to dig into the wiring diagram a bit more. I do get power to the plug - but I don't know if it is correct. I also need to look deeper into the multi-function switch.
 
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Unfortunately, wiper motor control has always confused me. None of the vehicles with which I was involved had wipers. For instance, I can't wrap my head around everything inside the schematic for the MFS and the wiper motor:

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That said, the first thing I'd do is check the ground conductor by bypassing the wiring harness ground circuit and going directly from the motor connector the battery negative, since it's not uncommon for ground paths to be disrupted by corrosion. According to the manual, the ground is through Pin 4 on the motor connector:

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How are you testing for power. This would be a good time to use an incandescent test light, not a volt meter.
 
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sab said:
Unfortunately, wiper motor control has always confused me. None of the vehicles with which I was involved had wipers. For instance, I can't wrap my head around everything inside the schematic for the MFS and the wiper motor:

View attachment 523570

That said, the first thing I'd do is check the ground conductor by bypassing the wiring harness ground circuit and going directly from the motor connector the battery negative, since it's not uncommon for ground paths to be disrupted by corrosion. According to the manual, the ground is through Pin 4 on the motor connector:

View attachment 523571
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Thanks, Sab. I'll give it a shot. I had trouble dissecting this as well - but did not spend too much time on it yet.
 
If you're getting power to the plug, like Sab, I'd start with the ground.

Also, have you applied power to the new and old motors yet to see if either work? Your original might be fine, or you might find the new one to be a dud.
 
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BlueC said:
If you're getting power to the plug, like Sab, I'd start with the ground.

Also, have you applied power to the new and old motors yet to see if either work? Your original might be fine, or you might find the new one to be a dud.
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I have applied power to the old motor, hitting the ground, and putting power to the other connectors, and no dice. I assume it should be that simple, but not sure.

I have not tried it on the new motor.

I did go ahead and order a multi function switch, just in case.
 
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NashvilleTJ said:
I have applied power to the old motor, hitting the ground, and putting power to the other connectors, and no dice. I assume it should be that simple, but not sure.
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I'd think so, but I don't actually know.
 
NashvilleTJ said:
I have applied power to the old motor, hitting the ground, and putting power to the other connectors, and no dice. I assume it should be that simple, but not sure.
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BlueC said:
I'd think so, but I don't actually know.
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I don't think it's that easy. About a decade ago, I had trouble with the rear wiper motor on my Expedition. I don't know how wiper motors work, and I never figured it out, but I did notice that you couldn't just apply voltage to the motor to test it. I think it has something to do with how it "parks" itself when power is cut off.
 
sab said:
I don't think it's that easy. About a decade ago, I had trouble with the rear wiper motor on my Expedition. I don't know how wiper motors work, and I never figured it out, but I did notice that you couldn't just apply voltage to the motor to test it. I think it has something to do with how it "parks" itself when power is cut off.
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I was thinking that as well. Motor could be fine.
 
Mike_H said:
I'm assuming, but sometimes voltage can be present, but as soon as you throw a load on a circuit it will act up. Incandescent can add the load you need.
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This is dead nuts on. An ohmmeter, by design, puts a very small load on the circuit (because if it put a significant load on it, the measuring tool would affect the measurement.) I don't have a power probe, nor have I ever used one, but I would suspect that it can put a load on a circuit somehow. It seems that would be one of its functions.
 
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sab said:
This is dead nuts on. An ohmmeter, by design, puts a very small load on the circuit (because if it put a significant load on it, the measuring tool would affect the measurement.) I don't have a power probe, nor have I ever used one, but I would suspect that it can put a load on a circuit somehow. It seems that would be one of its functions.
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I thought the power probe was pretty cool, and would work great for testing the motor - right up until I actually tried to test the motor…
 
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NashvilleTJ said:
I thought the power probe was pretty cool, and would work great for testing the motor - right up until I actually tried to test the motor…
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Yeah, I've considered buying one a few times over the years, but I just couldn't see what it can do that I can't do with my DMM and 'scope.
 
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