dpender1

Thanks Everyone in advance for the help, and this forum. I have a 1998 Jeep Cherokee 4.0 auto, 180k miles. I purchased it from the original owner who hasn't had any of the problem I'm about to describe. The problem is it blows the mini fuse in the pdc under the hood and the jeep quits running, though the fuse isn't marked, it's the 2nd one in from left side on the first row towards the front of car, a 15 amp. once it blows the fuse it's just like turning off the car. I've gone several trips between 7 to 40 miles testing it, before it blows, but once it does I have to wait 15 minutes to 2 hours before replacing fuse or it will blow as soon as the key is put in on position. Before the fuse blows the jeep runs and shifts perfectly. Brief history of what has happened and what I've replaced. 5 months ago is when it all started, pulled the car in drive, turned it off, came out started to leave and the thing died, discovered the fuse blew, replaced it and went on my way, made it 2 miles and it died again, kept blowing the fuses as fast as I put them in, Had the jeep towed home, I pulled 2 codes one was bus bar power failure and a po700 generic trans code, I replaced the the transmission control module(after doing a search on this forum) and no more problems, every thing worked perfect, until a month ago, Then it started all over again, so I replaced the TCM again(Several Times) the problem still continues. I did a search and if correct the fuse is F22 for fuel pump?? The jeep will sit and idle in park all day long, only blows the fuse after you drive it. I sealed the windshield 5 months ago thinking under the dash was getting wet causing the TCM to short out, so I let it run for 5 hours with heat on to dry the sealer. I recently let it idle for 2 hours testing it, before I replace the fuel pump, would it be normal for it to idle and drive fine until the fuse blows if the fuel pump is bad? it again is pulling codes for bus bar power failure, and po700, Here's the list of parts I've changed trying to figure this out, (while most of them are used parts from the junkyard I tested every thing I could) All the selonoids in the trans and trans service, Range senser/ NSS, speed input and output sensers, 4x TCM's, Alternator, Ripped the dash apart and checked all connections to gauges, relays, evap selonoid under hood, I've checked the o2 wires all looks good, checked the fuel pump molex plug looks good, I recently changed jobs so I don't have the coin to take it to a shop and ring up a big bill,but have talked to a couple of mechanics who have said the '98 had electrical problems ????? any help would be very much appreciated!!!!!! I feel like this guy

DFlintstone

I have an idea. Since it will idle, and dies when the fuse blows, you don't even need help. Leave it idle, go under and giggle wires. The wires to the rear 02 sensor are a known culprit, but you mentioned it was OK for a bit after you changed the speed sensor. Wires chafing/grounding...happens! Leave no stone unturned, poke around till you kill it...could be near the front 02 sensor, anywhere on the way to, or at the rear one. Good luck!

dpender1

Dflintstone, Thanks for your reply, I'll give it a try, Thanks again

dpender1

bump, anyone else had this problem or have any ideas? Thanks

CCKen

Refer to the Fuel Pump diagram below.

It could be the wire that splits off at the fuel pump relay in the PDC and that goes to the PCM. Note that it goes through connector C107, which is located at the trans dipstick tube, along with two other transmission related connectors (see pic). Examine the connectors and the wiring at these connectors for chafing and wires shorting to ground.

With the engine running (F22 not blown) wiggle the wire looms that are associated with the three connectors at the dipstick and see if the fuse blows.

Problems in this area have come up before.

FP diagram:



Connectors at the trans dipstick area:

C107 is the larger of the three connectors. Note also that 1998 connectors may be a different color.

dpender1

CCKen, Thank You!!! I've seen other post where you've helped people out when I did a search on electrical problems, I was hoping you'd respond to my post, your attention to detail, knowledge and pics are amazing!!!!!!! I will try that tom. night after work and post back. Thank you again

DFlintstone

CCKen

What.....

CCKen

dpender1,

When you say "it again is pulling codes for bus bar power failure", what code number was that?

dpender1

CCKen,
I'll have to check it this evening when I get home from work and I'll post it then it was 16xx but after that I'm guessing. My wife is going to try looking at the connections you posted, if she gets a chance today, otherwise I'll do it right after work. Again many Thanks for your Help.

dpender1

CCKen and DFlintstone,
The code is 1694. I went back a 2nd time and checked/wiggled the wires on both 02 sensors and checked/wiggled the fuel pump plug as DFlintone had suggested, still running and all looks good, ( not that it means anything,but the 02 sensors are about a year old).
I went and checked/wiggled the three connections that CCKen was talking about, there was no change and all looks good, nothing burned,bare or chaffed etc. The molex plugs and connector pins all look good, nothing burned or corroded on male/female terminals.
My son finally talked to one of his neighbors whose a mechanic and into jeeps( he has a lifted Cherokee and several other cool jeeps) unfortunately he doesn't have time to look at it right now, but he said look at the wiring for the liftgate and doors for interior lighting, and taillights, because they get their power off that same circuit, That there is only three power sources/circuits in the PDC and the one that is blowing- powers the lights. does that make sense to you guys? He said since it's been running and shifting fine before it blows the fuse, and with all the stuff I've changed I should concentrate on the lighting end and eliminate that, which should be easy to find as many times as I've blown the fuse, I should find bare burnt wiring. He also said '98 had a problem with the liftgate wiring being to short or tight- figured it's worth a try unless you guys say that's wrong. I'm willing to try what ever you guys come up with as I need to get the Cherokee back on the road. I very much appreciate all the help from both of you. Thanks Guys

CCKen

Here's P1694:

"DTC P1694 will set if no CCd bus messages are received from PCM for 20 seconds or invalid messages are received for 20 seconds.

Possible Causes Failed Crank Position Sensor
CCD Bus (-) circuit open between PCM and TCM.
CCD Bus (+) circuit open between PCM and TCM.
Transmission CCD bus wiring damaged.
Faulty TCM.

It's hard to associate P1694 with the fuel pump fuse blowing, except that some trnsmission wiring and the fuel pump wiring goes through connectors C100 and C200. Both are located under the dash on the left side. If there's corrosion in one, or both of these connectors there could be a short circuit that's causing all your problems.

Was your Jeep ever in deep water, so much so that water got under the dash? If you're not sure, is there a high water mark under the dash?

If you pull the trim panel and the knee blocker from under the streeing column, C100 and C200 are on the far left under the dash. C100 has a bolt in the center of it. See if you can get at these connectors and wiggle the hell out of the wiring to see if the fuse blows or the CEL pops on (for P1694). See if the connectors are scure (hard to do), and the wiring in the area is okay.

About all I can suggest at this time.

EDIT: "I sealed the windshield 5 months ago thinking under the dash was getting wet causing the TCM to short out,". Bingo!

dpender1

CCKen,
I just came in from taking the liftgate and taillights out, I didn't see any bad wiring there. As far as being under water I can check with the P.O as I know him. The reason I thought that behind the dash was getting wet, was prior to me caulking the windshield the drivers side floor board would have a puddle every time it rained, but I never saw where it was coming from, also the climate control only works on high, it has been like that for a long time from what I'm told by P.O, it's been changed and so has the resistor, blower still only works on high,but I figured maybe was also caused by water getting in. Since I've caulked the windshield 5 months ago there has been no more water on floor. I will check those connectors like you suggested. When I recently pulled the dash apart I called myself taken every molex plug I could find apart and cleaning it with contact cleaner,but I will check for those specific plugs. Makes sense if something is corroded there would be the problem. To clarify the blown fuse problem hasn't weather specific, temp specific or road condition specific, also it has done it driving 55 and sitting at a stop sign/light, very unpredictable. I will post what I find. Much Thanks

dpender1

Just went out and checked those plugs as I had the dash open, shook the snot out of the wires both side of plugs nothing changed, I will take it apart tom. inspect and clean. looks like both have bolts through them. Are the crank position sensors known to work intermittent? are they hard to change?
Thanks

DFlintstone

I'z just clowning Ken, all is well! dp, as you mentioned you have one of the best for your year here. (Ken) All I have other then the "affore", is to maybe run it and try to see if any particular action causes the failure. Breaking. accelerating, hitting a bump ect...

It might have been TJwalker that mentioned wires to the rear 02 can blow a fuse that takes out the ASD relay. I have no ASD relay, or experience with the newer! Best of luck to you.