So I'm having an issue with my 89 Cherokee Renix 4.0. One day my wipers just didn't turn on when I tried - they stayed parked, and never budged. I shot the wires and got 12v with the key in start position / wipers on high. I swapped the motor with a remanned Cardone a few months back, and it worked again perfectly fine (on low and high, I deleted the intermittent wiper delay module under the steering column, it didn't work anyway).

About 3-4 months later, it started randomly dying out while in use - it would randomly park throughout the swipe, and eventually when it would park in the normal parked down position, it would just die and not work anymore. This got worse and worse for a few days until it just stopped coming up from park. Then when they were parked, and the position was set to "high" I could kind of force them to swipe, and once a bit of pressure was applied, the motor would cycle them 1 or 2 times and then park again, and not turn back on.

I looked at the plug for the wiper motor today and did see some decent amount of (new) corrosion on the #4 pin. I scraped a bit of it off quickly on my lunch break, put it together - still nothing. Getting 12V between 1 and 4 with wipers set to high, and -12v with the wipers set to off position. Also, smacking the motor with my screwdriver decently hard wasn't starting it up either. I have my doubts it's the motor...but it is under warranty if it's bad. Every once in awhile, particularly when I first start up, the wipers will work for a cycle or two and die again...when they do cycle, they seem to be a power draw on the entire jeep (when the cycle happens it seems to dim the lights/air vent)...bringing me to my next symptom:

In the last few days, I've noticed my lights dimming every few seconds (very slightly) when in idle, particularly in the mornings when I just start the jeep (headlights and dash lights) - once the rpm's go up, it doesn't happen whatsoever, until it idles again. I suspect an alternator.

- The battery is pretty much brand new, just swapped it like 2-3 months ago with a brand new one.

- I ran a secondary ground wire under the dash to the instrument cluster ground (one of cruiser's tips)

- The negative battery cable is also brand new. The grounding point on the dipstick/engine was refreshed recently. I did have a question about the back strap - is it ok to leave it on and just refresh the firewall side of it, and run a second 4awg ground to the back fuel rail bolt, without doing anything to the valve cover bolt? I figure even if the strap is shot, it would still suffice running a second ground to the firewall, which I did, and was too lazy to get at the back nut.

- The cap/rotor/plugs/wires are also brand new.

As for an alternator test - what is your guys' take on disconnecting the battery during idle? I did this awhile back to test the alternator before replacing my battery, and it ran fine, thinking about trying it again here. I have heard that with older vehicles like these it IS safe to do this, but still kind of unsure.

 

Update : alternator is just about shot. Turned off twice in a row when running and pulling the battery off, and you can tell it's killing the lights at idle.

Will update in a few days when I get another one in there I'm pretty sure the wiper motor is a separate issue though...