1978 Intermittent wiper conversion

[fasteddie]

My conversion from the original 2 speed wipers to the upgrade intermittent wipers worked great initially. While driving in the rain the delay feature stopped working. I have checked my ground and connectors but I don’t find anything wrong there. I’ve replaced the new LMC module to get the very same results. The wipers run fine in slow and fast and in intermittent. Just the delay stopped working. Any input to help me find the problem. LMC has been generous to supply another module but now has basically told me to check grounds and connectors or they will refund the purchase price. No tech support these days. I loved the delay while it lasted. What could I be missing. I don’t want a refund. I want intermittent wipers. Thanks in advance for your input. LMC says there’s been plenty of these modules sold and no other customers complained of failure.

 

[Sparky83]

Did the intermittent conversion contain a relay??

 

[fasteddie]

Yes. It’s mounted to the circuit board in side the little black box. Similar to the OEM setup.

 

[Sparky83]

Everything i could find for it said the relay tends to be the problem when just the intermittent stops working. The only other mention is a failed circuit board in the wiper motors or bad contacts at the wiper motor.

Circuit board on the motors was mentioned with newer vehicles so dunno if the 78 would have one or not since they were in their infancy in vehicles then. But could still be the contacts.

 

[fasteddie]

Thanks. When I replace the LMC part with a new one everything is great for a short time. I test it once I have it connected and wait for a chance to drive the truck in the rain. When it rains I test it again briefly before I turn it on and leave it on. I haven’t timed the operating unit to see how long it lasts but it’s not long. I’m currently using the slow position on the switch because I have it all working at the moment. I’m raking my brain trying to figure out why it’s failing. I have a feeling if I turn it to the intermittent position and leave it the delay will fail at some point and leave the wipers running without pausing. LMC has offered a refund of my purchase price but no more replacement modules at a 100.00 dollars a pop. They say “ no other customers have reported any problems with this part” It’s a head scratcher for me. How could I go about finding the cause of this failure if it’s the circuit board that fails? What could cause this? I’m missing something.

 

[Sparky83]

That part i cant answer. It was just what i could find online for the same sounding condition. But they were factory installed units. So dont know how the conversion units act. I know when my dad tried to do the same with the corsica we had at the time it wouldnt work at all.

 

[fasteddie]

The reproduction part seems to duplicate the factory setup. The operation must be engineered to clone the parts that Ford built beginning around 1978. I’ve never had a factory built unit so I’m not sure what’s inside the “box” I imagine a circuit board built very much like what these new offerings by LMC looks like. I wish I could see the diagram of the switch wiring as well as the circuits on that board. Maybe then I could understand how to troubleshoot this. The slow and fast positions are more than likely two different grounds provided by the switch. I have no idea how they delay the action of the slow wipe when it’s in the adjustable intermittent setting. Again the motor itself has never failed to run correctly. The delay feature stops. If anybody reading this has experience with this part from LMC truck parts please help me out. Thanks

 

[fasteddie]

Now I’m thinking about the “new” intermittent switch I added when I put the delay module in place. Until now I have only considered the modules as being faulty. Could it actually be the new switch causing my module delay feature to fail? Should I order the switch from LMC truck parts to be sure it’s a match for their component they offer. The intermittent switch I have came from NAPA.

 

[fasteddie]

Could someone post a link to help me test my intermittent wiper switch that I installed with the aftermarket LMC intermittent wiper control module. I’m still searching for answers to why the delay feature on these LMC modules fail. If there’s someone that can shed some light on this testing to help me pinpoint my failure it will be greatly appreciated. If I’m posting in the wrong forum please direct me to the correct place to get some expert advise. Thanks for the support guys.

 

[Jasperrc]

I have no experience with the LMC conversion so I'm afraid I can't help with troubleshooting it specifically.

To do the conversion on our truck, I snagged a salvage yard switch and harness from an early 80's truck and it went in pretty easy. As I recall there was a dedicated ground wire and the black box needed a good ground where it mounted to the dash.

Here's a link to the service manual pages for wipers on our trucks. If the LMC setup is similar, maybe it will help:

1978 Ford Shop Manual Vol 3&4 - Group 35 - Auxiliary Equipment

www.fordtruckfanatics.com