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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.
I watched a guy take apart his PCU out of a 1991 YJ and it had 3 capacitors, all the same, 220uF, 25v, 105C.
I took mine apart and I have 2 of those same capacitors and one 470uF, 25v, 105C big capacitor. So had to order that one special, another few more days tacked onto this project. It's just more surprises every step of the way, I never imagined getting so deep into this after driving my Jeep one day and the next day it just wouldn't start at all. No warning symptoms, none that I noticed anyway, might have been slight rough idle or loss of efficiency (mpg), but it still had power on demand, in reserve. This one takes the cake for me.
You can see the large 470uF capacitor behind the smaller 220uF in the front. So strange.
I watched a guy take apart his PCU out of a 1991 YJ and it had 3 capacitors, all the same, 220uF, 25v, 105C.
I took mine apart and I have 2 of those same capacitors and one 470uF, 25v, 105C big capacitor.
Well, during my attempted repair of the PCU for this 1991 Cherokee I was using the cap of a pen, the kind that has a clip to fasten to your shirt, the clip is plastic and makes for a perfect gel picker while being soft enough to not damage the PC Board. So, as I'm cleaning gel out I got down to where I could see the board and I noticed I could see copper. I thought, that's not good. It was a small piece, so I kept going. However, the capacitors were covering most of the area where I was working. Once I cleared around the caps and got the backside clear, I used my soldering iron and removed the capacitors. Thats when I noticed the burnt black goo that I noticed running on top of the gel in one of my first photos posted. The bottom of the 470uF resistor was blown out, the gel was all discolored around it, and there was black stuff running all the way under both resistors. As I cleared the black stuff away with a soft bristled toothbrush it revealed bare copper trace under all of it. I don't know what that black stuff was, but it caused the 220uF base holes to short. When I tested the negative side hole to the other hole my meter beeped. Neither of the other two capacitor holes showed connectivity between the two holes. All three negative holes are on one trace, they all rang out when tested. but that other hole should not be connected to the negative hole. Somewhere the negative trace is touching the other trace so I'm sending it to a local shop to have them finish the repair. This has gone beyond my scope of abilities. Also, I coach soccer and I should have been out with my team weeks ago... with my current situation this Jeep is my primary driver and the parents on my team are starting to send me emails asking when we are going to start practice, we have games in 3 weeks. It's time to give this project a rest and go buy a reliable car.
