Wipers burnt

[Zonaman]

Ok need some help with this one!

I had recently installed the intermittent wiper module (Revolution Electronics) in my 69 half ton. Worked fine. Today, driving down the freeway, the wipers start wiping. Switch in off position. Couldn't get it to shut off! It was switch in off position but wiping on regular,slow speed and I couldn't get it to go intermittent or any other settings. I pulled off, turned engine off. Ignition on again. Went back to wiping. So I stopped the engine and pulled the fuse. That stopped it. Back on the road and I smelled something electric burning. A puff of smoke from center in the general area of the wiper switch and motor area. Pulled over looking under the dash with a flashlight. Couldn't see anything obvious on wiper switch, intermittent module or wipe motor, like burned wire or scotch mark. At least as well as I could see. Pretty sure it was the wipers. Any ideas on what might have happened and where to start on this one? Thanks

[RustyPile]

I'm not the least bit familiar with your after-market intermittent module.. But I do know how the wipers work in factory form. The wiper motor has voltage applied to it whenever the ignition switch is on. The wiper switch provides the ground path when it's turned on to either speed position. Here's where the assuming begins.. I assume the intermittent module provides the "final" ground path and has voltage applied to it also. The module has probably failed and has developed a short to ground. Removing the wiper fuse removed the voltage to the wiper motor and it stopped. The module still has voltage applied to it and has "self destructed".. Try removing the module from the circuit and I bet your wipers will function as designed from the factory..

[VetteVet]

After looking at the website, I can't determine if the control module uses the positive or negative circuit, or a combination of the two. You should be able to answer that question as you wired it into the wiper system.
The stock system is wired as a constant positive with the switching done on the negative(ground) side. Removing the fuse kills the power to the motor so I would assume that the or the wiper switch could be where the problem lies.
There could be a short in the switch between off and the low-speed wire on the switch or there could be a break down in the module which only allows the low-speed function to work.
I would begin by removing the switch and checking it for correct functionality with a multi-meter. If that checks out ok then I would remove the module and wire the system back to stock. If everything works as expected, then I would contact the vender and ask them if they would exchange the module for a new one. They may or may not do that depending on the amount of time that you have had it installed.

[VetteVet]

Rustypile beat me to the post. I see that we agree totally.

[Zonaman]

Thank you everyone for your replies. I will get under there soon as I can and begin testing hopefully we can take it from there. A procedure for testing that OE switch would be appreciated.

[ray_mcavoy]

Originally Posted by Zonaman

A procedure for testing that OE switch would be appreciated.

You can test the OE switch with an ohmmeter (multimeter set to the resistance/continuity scale).

With the switch in the OFF position, there should not be any continuity between the switch body (ground) and any of it's 3 terminals. It is normal though to have a connection between the low & high speed terminals (those are the outermost terminals on the switch).

When you turn the switch to the LOW position, you should then have continuity between the switch body and both the low & high speed terminals.

Turning the switch to the HIGH position should open up the connection to the low speed terminal, leaving only the high speed terminal connected to the switch body. The high speed terminal is the one that's a little farther away from the other 2 and off at a little bit of an angle.

Finally, pushing the washer button should give continuity between the switch body and the WASH terminal (that's the middle terminal).

[VetteVet]

Pretty simple:
If you can get to the switch pull the plug off and check continuity to ground from the
off terminal. Should be infinity. Check from the low speed to ground, should be zero ohms .Check from high speed to ground, should be zero ohms.

Check from off to low, should be infinity.

check from off to high speed, should be infinity.

Check with switch in low pos, should be zero ohms to switch body, and the low and high speed terminals.

With switch in high, check for zero ohms between the high terminal to the switch body.

The push in feature grounds the washer pump. You can check this to the switch body for zero ohms.

The switch is grounded to the cab or should be.

Again I'm slow on the draw. Thanks Ray.

[VetteVet]

Here is a complete write-up on the wipers.
http://67-72chevytrucks.com/vboard/s...d.php?t=413551

[Zonaman]

Originally Posted by ray_mcavoy

Finally, pushing the washer button should give continuity between the switch body and the WASH terminal (that's the middle terminal).

This reminds me, I do not have a washer pump. I just leave these wires unconnected. No problems with that, I hope?

[ray_mcavoy]

Yeah, no problem with leaving the washer pump wiring disconnected if you don't have one.

Just make sure the power feed to the washer pump (typically a yellow wire connected to the same circuit that powers the wiper motor) isn't in a position where it could accidentally short to ground.

[Zonaman]

Originally Posted by RustyPile

... Try removing the module from the circuit and I bet your wipers will function as designed from the factory..

Winner! Upon close inspection it was plain to see the module burned through. Let's see if LMC refunds me.

Being in this part of Arizona you don't get too many occasions to use your wipers but they are mission critical!

Thanks again to everyone.

[VetteVet]

I,m sure you know that there are aftermarket washer pumps out there that you could easily install in the reservoir outlet line, or even a replacement reservoir with the pump attached. The wiring is super simple. Just locate the old washer pump wire and splice it into the new pump ground line, and then run the pump positive wire directly to a fused positive source and the pump will be switched on the negative side just like the OEM pump.
When you push the washer button on the wiper switch, it activates the pump.
There are also venders on here that sell the OEM pump , I think.
Let us know what LMC says.

[Zonaman]

I think I still have the hoses for it but I just never got around to it.

[RustyPile]

Originally Posted by Zonaman

I think I still have the hoses for it but I just never got around to it.

OEM and reproduction GM washer pumps are readily available at your local auto parts supply outlet.. Or if you are inclined to order online, Classic industries has them..

https://www.classicindustries.com/pr...rts/72332.html

[HO455]

Sorry to hear the delay failed. If you get no joy from LMC I would contact Revolution Electronics directly. I had an issue early on with mine and David was helpful in solving it even offering to replace the unit. Fortunately the issue solved itself and (Knock on wood!) 40k miles later it's still going strong. Better than the wiper motor is working at present. Which seems to be going south on me. I guess it's time to find a low mileage truck from New Mexico to donate it's wiper motor.

[Zonaman]

LMC wasted no time in refunding my purchase- no questions asked. I'm happy with those people. Not sure what to make of it all since I've heard of very few problems with this sort of modification. Naturally, I'm not overly eager to go rolling down the 101 in Scottsdale with smoke billowing out of dash again so I'm very reluctant to attempt intermittent wipers again.

[ray_mcavoy]

Glad to hear LMC gave you a refund on the failed intermittent module.

So do the wipers operate normally now with the module removed? And how are they in terms of speed? Relatively normal or do they seem a bit slow/sluggish? The reason I ask is because sometimes the lubricant in the wiper motor gearbox and/or linkages gets dried out with age. That makes things stiff to move and places excessive load on the motor. Which would cause the motor to draw more current and might have possibly been what contributed to the burned out intermittent module.

[Zonaman]

Originally Posted by ray_mcavoy

Glad to hear LMC gave you a refund on the failed intermittent module.

So do the wipers operate normally now with the module removed? And how are they in terms of speed? Relatively normal or do they seem a bit slow/sluggish? The reason I ask is because sometimes the lubricant in the wiper motor gearbox and/or linkages gets dried out with age. That makes things stiff to move and places excessive load on the motor. Which would cause the motor to draw more current and might have possibly been what contributed to the burned out intermittent module.

They operate as they did before the module went in. But they were alway kinda sluggish. How do you lubricate that gear box?

[RustyPile]

Originally Posted by Zonaman

They operate as they did before the module went in. But they were alway kinda sluggish. How do you lubricate that gear box?

The wiper motor gear assembly is serviceable but the procedure it too lengthy to post here.. The procedure is thoroughly covered and explained in the Factory Service Manual, Section 12... If you don't have the manual, it is available in several sites, most are free downloads.