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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
This will allow us to move the relay and TR2 transistor enough to make room for 1/2 a heatsink to be added. This option has the most flexibility; multiple different heatsiniks can be used, they all just need to be cut in half.
Taken another step further, the TR1 transistor can be centered in the available space, making room for an off-the-shelf heatsink. I did not find a whole lot of suitable options in the couple minutes I looked but at least one would work.
Last edited by Jim Malcolm; 01-10-2021 at 09:50 AM.
There seems value to me in eliminating the SMD components and instead having a design with human-serviceable parts. Here is a layout using a cut heatsink
And another using an off-the-shelf heatsink
And so there it is. I'm 99% sure I know how the whole circuit works but since I'm not 100% sure, I'm not going to spout off my opinion. If someone is confident they know how it works, have at it...
Last edited by Jim Malcolm; 01-10-2021 at 09:52 AM.
If anyone is interested I was able to repair my module.
The only electro-mechanical part on the board is the relay which from what I could find is an old obsolete low quality relay. I removed the relay and found a direct drop-in cross Hongfa America P/N HF3FF-012-1ZST which can be purchased from Jameco for under $1 https://www.jameco.com . The other two possibilities are the quad logic gate which is an old P/N but I found a replacement P/N CD4093BE it on Mouser http://www.mouser.com for under $1 and a power transistor that I could not get a good read on it (I suspect that it is a mosfet) but fortunately the relay did the trick on mine.
Be careful, the board is covered in silicone conformal coating which needs to be gently remover from the solder pads and the board is low quality so the pads can lift easily.
I replaced the wiper motor with a Cardone rebuilt one a little over a year ago thinking that it was worn out and now with the module working I come to find out that it is crap!! Time for a trip to the U-PULL-IT.
Same story with the Renix era cruise control moduals. Plastic box with a printed circuit card full of soldered on resistors and transistors inside. Fixable DIY analog electronics.
I don't know about the cruise control module in the 91 and later era. If anyone knows if it's analog or not please speak up.
Greetings fellow XJers. I'd like to discuss resurrecting this project. This is by no means my area of expertise but I work with a few EEs who could probably help if I can show them a schematic. Based on what firawan242 has done above, it seems to me the next step would be to determine the connectivity of all of the inter-layer connections to figure out the parts of the circuit that we can't see, and then, a full schematic could be created. Am I correct in that line of thinking? Am I missing something? Have you started a schematic at all firawan242?
Going down a different path, does it make sense to redesign this circuit to use a 555 timer chip instead of the relatively obscure MC14093BCP? If I'm reading the MC14093BCP docs correctly, the downside of doing so is that the 555 chip has a very abrupt waveform, with the return switch in the wiper motor doing most of the work while the MC14093BCP looks like it would drive the motor longer. Maybe I'm wrong (more than likely actually...) But anyways, a fine fellow Jeeper over at Jeep Forum did an install using a MXA041, which uses a 555 timer chip. If you click on the "Download User Manual" link off of the below, it shows the schematic; seems easier to implement than what we're dealing with. Plus it's all human size components instead of those tiny PITAs I can barely see any more. The downside of the MXA041 is the same as the OEM board; marginal spec components that warrant an external relay. If we're going to do this, let's make it bullet proof is my thinking.
Unfortunately I haven't do any schematic yet. I am trying to draw a schematic using PCB software which has features to do that job. Again, I'm still a newbie in electronic. I need time to learn about it. If we can figure out what is Motorola 689T01 or figure out the substitution include all the diode at least e can move forward to try remanufacture the wiper delay module.
I prefer to rebuild or remanufacture the old rather than modify it which ight need some modification on existing wiring harness. Yes, there is opportunity to use the old box and pins and redesign the working 555 circuit and build it into the old box. It still big job for newbie like me....
Moving a few things around, I get the following full schematic. Traces highlighted in red are high level signals, mostly just pass-thru, that I've replaced with labels embedded within. For clarity, I've removed this connectivity on subsequent images. Relevant connectivity in the wiper stalk and motor switches has been added.
Wow Jim,
You did a great job...I still learning to figure out that schematic...Now we have a new hope to solve this problem
Unfortunately, no I have not. I thought about contacting www.revolutionelectronics.com/ and seeing if I could convince them to make one for later model Jeeps, but then Covid hit, and quite honestly, for the little bit I drive anymore, I've just been nursing it with high wipers and activating the manual wipe as needed when it's raining less than that. I picked up a 555 timer based board with thoughts of converting things, but never really went anywhere with it. I'd love to see a replacement for these.
That's how I drive with mine, too. It would be great to develop a replacement module, it seems like there would be a market for them. Used oe about to fail modules sell on eBay for $50 to $75, and I've see a few generic intermittent wiper boards with **** speed adjusters, I just don't know enough to know if they could be modified to work. If you ever want to investigate it further let me know, I'm definitely interested in it as a product project. Thanks, Andy
There are no new replacement modules, and I haven't seen any nos modules, either. There are plenty of used ones available, on eBay and elsewhere on line, and in yards. The problem is they have a very high failure rate with leaking capacitors, overheating, and a weak circuit board. Even if a used one is working when you buy it there's a high probability that it will fail, too. Repairing one is not that difficult if the board isn't excessively damaged like mine, and there are a few good write-ups about replacing capacitors, which ones are needed and where to buy them. High and low wiper speed does work with the module removed and the plugs connected directly to eachother.
My '92 XJ is having wiper control issues. The I.W.M. has a P/N SF8956000428. (model year MIXED build has caused problems finding the right parts in the past.) This is not the part listed in this thread. I suspect that mine is an obsolete part but with the same function and pins as the "AB" mentioned in this thread.
A different P/N than this post references, but there is a pointer somewhere that the P/N changed.
The circuit board is very different, but I am pretty sure the function is the same. The connector pinout seems to match. Is it really??
There is reference to bypassing the I.W.M part by plugging the two connectors together. That seems like it should work, BUT.., The connectors have different #of pins. One is 6-pin, the other is 7-pin. Does this really work? I still has to get to know the signals on each to be sure, but any tips would be appreciated.
The problem I am having is as follows. When I turn on intermittent, the motor seems to run smoothly. When I switch to LOW speed or HI speed the motor sweeps the blades very erratically. When I turn OFF the Wipers, the motor runs to the park position at a smooth, normal speed.
I rather suspect that wiring of power or grounding may be causing the LOW and HI speeds to get bad current source somehow and that the other two modes (intermittent HI and PARK) get adequate power.
I am newly back to the cherokeeforum, in the hopes of keeping the 30 uear old beast running!!
01-10-2021, 09:04 AM
