The big "I" word we all hate to see. Intermittent. Over the years my truck has had a problem where it just dies like you turned off the key switch. Doesn't matter if it was being driven down the highway or sitting idling. But it only did this whenever it would rain. Never during dry weather. Wouldn't matter how much or how little it rained either. Or so I thought . . .

Yesterday, dry as a bone outside with clear skies, for the first time I realized it had nothing to do with the rain. I was filling my washer fluid reservoir and the very second I turned the wipers on the engine died like it always did "when it rained". Turned the key and it started right up, just like it always did before whenever it rained (whenever the wipers are on). It only does it on occasion though not every time.

So once this light bulb came on, I set the wipers on intermittent. I had to sit there letting them wipe intermittently for 20 minutes before it happened again, but it did happen. Just as the wipers began to move the engine died. What can be causing this? Well, the wiper circuitry yes but how do I troubleshoot/remedy this?

 

Bump this. Sounds freaky.

 

Two reasons I've heard of for this: water getting to the GEM thru a bad windshield seal, and an iffy CPS, especially aftermarket CPS. I have a F4TZ-12K073-C CPS. Here's a thread on the subject, and there are more, so enjoy the search function!

 

David hit it right on the head there. Some of the parts warehouse CPS's are prone to electrical noise. I would change it out with a Ford or an IH model.

 

Thanks guys y'all gave me some great reading material. I read it all and the links, within the links, within the links ad infinitum. I drove the truck to the International house in Sherman and back which is about a 75 MRT and the big ol gal never missed a beat. They only had the gray CPS but I got it anyway since no blacks or blues are available anywhere that I know of.

Talked to the guy behind the counter real knowledgeable guy. Said the ones being produced now for International are supposed to be the most reliable to date. I can't vouch for that obviously but he impressed me as a guy not one to talk just because he likes the sound of his voice, so I think and hope he is correct.

I didn't run the wipers when I got home because I did it enough yesterday, and saw enough failures initiated at the onset of the wiper motor being given power that I know for certain that's what killing the engine. Rain/moisture is not the culprit as I had thought all these years.

Well there's a brief update - mainly just wanted to say thanks. Now I have to locate the section that teaches me how to replace front end parts. Something is really loose down there.

 

Would you be willing to do an experiment?

Some background: another radio frequency issue seen on these trucks is an HID headlight kit interfering with a performance chip, causing the engine to stall. The fix for that is an RF choke on the HID power line and/or the chip cable. As an experiment, place an rf choke on the CPS wires and try the intermittent wiper test.

If you have the time and inclination it seems like a good opportunity, but naturally just getting the truck fixed is the priority, so no pressure.

 

I could do that. Could you suggest the best vendor for an RF choke? I also am going to upload my superchips back into the computer. I took it out when I started having problems to see if that as possibly the cause. The engine performs an order of magnitude better with the superchip loaded. I don't have a HID headlight kit and don't plan on installing one but you never know - I might get tired of that awful yellow lighting at some point.

I haven't swapped the CPS yet with the new one so I'll wait until I install the RF choke and do some testing before and after the choke install.

 

I got my RF chokes at the local Radio Shack, mostly because shipping would cost more than the item, but there are online places that sell various capacities if you want to get fancy with it. There's a thread about that somewhere.

As for placement I'd think closer to the CPS is better, but zip tie it to something solid so it's not yanking the wiring around while in motion.