1988 Jeep Cherokee Laredo -- Transmission Fluid/Filter Change; TSB on Brake/Shift Interlock; Seat Belt Question

Hi. Just inherited a 1988 Jeep Cherokee Laredo (4 L Auto). It has less than 25K miles and is really clean. Didn't get driven much over the years so worry about dried out seals and the like. I've changed some fluids and opted to have the local Jeep dealer do the transmission fluid/filter change. They noted (as I did looking at AllData) that it had a TSB/recall (#733) on the "Brake Pedal Shift Interlock." They moaned about it being a two hour job and only paying at warranty levels, but said they'd do it if I wanted it. It seems to be an idiot proofing measure related to the location of the pedals in the tight floor space of the Jeeps of that era. Doesn't seem like anything that would "improve" overall performance, longevity, etc. but rather give some measure of increased safety in the event you slam on the accelerator rather than the brake. Mixed reviews in the searches I've done. One guy noted that he had a surging engine on start up without the accelerator depressed. I've got that two and it usually only lasts for about 10 seconds tops before it drops down but it does get up around 3K RPM before doing so (doesn't do it every time). SEE his post:

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(1) Do folks out there affected by this recall (may be years ago for many of you) think it is worth doing? Any connections made between the surging I (and other apparently) have had? Any problems from doing the work ... especially on an older Jeep (the dealership seemed out of their element working on a 16 year old Jeep -- even if it was in mint condition)?

(2) On the transmission filter/fluid change ... the dealership quoted me a price of approx. $90 for the job. I came in dropped it off and found after four hours that they actually quoted me ONLY the labor and the parts would amount to ANOTHER $90. Ended up being a $180 job to replace fluid (cheaper Dexron rather than the ATF3 stuff for this older Jeep) and the filter. Sound right to you (the total at least)?

Finally, (3) I've noted just in the past couple of days that the driver's seatbelt (shoulder) doesn't appear to "catch" when you yank on it (as if in a crash). The passenger shoulder belt does engage the mechanism and stop coming out when given a good yank. Any ideas on whether this is a warranty item on such an old Jeep (given it is a safety thing)? Any known problems with the seat belts on this Jeep?

Thank you for the attention. Apologies for cramming all in one message but figured that it was better than a slew of separate messages (which I may try if this one seems to overwhelm).

Best,

BikeQuest

Reply to
BikeQuest
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Reply to
L.W.(ßill) Hughes III

25k in 16 years?? That was a real find - my 88 has 165k on it. The surge you mention is very likely a dirty/corroded connector to the throttle position sensor (TPS). Sits on the front of the throttle body - unplug it, clean both sides of the contacts as well as you can then plug it in and pull it out several times to break the film. Use a blob of silicone insulating grease to seal out moisture and it should be OK. It might also be a corroded spot on the sensor itself - it's a wire-wound sliding resistor so it will film over after sitting that long especially. With the key off, pump the accelerator a several times just to move it around, then take your foot off the pedal and start. That helps mine when it gets to the 'needs cleaning' stage.

Next time you go to that dealer, just bend over and grab your ankles to be ready for what's coming!

Reply to
Will Honea

Hi,

In response to your questions:

1) Skip the interlock mod and fix the real problem by replacing or repairing the heat-damaged TPS connectors and rerouting them so they don't get hot again. Also, there is an O2 sensor recall that you might take advantage of:

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2) Are you sure you need a new trans filter simply because it has been sitting unused? It doesn't show up on the regular maintenance schedule. As for the fluid change, the owners manual says "8.5 quarts total for dry fill. Approximately 4 quarts required for periodic fuel change as specified in Maintenance Schedules". Perhaps the partial fluid change is a reasonable DIY job, not sure. Maybe ask around at some transmission shops for a better quote. Anyway, you're not scheduled for your first change for another 5K miles.

3) Like yours, my seatbelt will not lock when tugged. I initially thought it might be defective, but I've since tested it on a few sharp stops at low speed and it locks up just fine. Not sure if it's slightly worn out, simply less sensitive, or if it uses a different kind of inertial mechanism, but it works.

Steve

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BikeQuest wrote:

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Reply to
Steve

On the transmission fluid change: The dealer I sometimes use for service tells me that my `89 Cherokee has no filter, just a screen. They also tell me that the pan gasket on that transmission is horrendously difficult to get right so it doesn't leak. This much I believe, since they were the third (and final) shop to replace the tranny pan gasket. Watch for leaks.

On the Shifter/Brake interlock. Yes, the interlock is an "idiot proofing" thing, but not the way you think it is. The interlock links the keyswitch to the auto shifter and brake pedal, but the TSB (I'm speaking of my `89 here, I'm assuming that your `88 is the same) isn't really about the safety issue. The interlock prevents you from (1) turning the key out of the OFF position with the shifter in any position other than Park or Neutral, to keep you from starting it in gear. When this interlock is out of adjustment you won't be able to turn the key far enough to remove it at shutdown. It also prevents you from (2) moving the shifter out of Park without first depressing the brake pedal. Again, when it is out of adjustment it makes it difficult to shift into Park and sometimes impossible to shift out of Park. My `89 Cherokee has exhibited all of the symptoms, even after the service was done. If yours isn't acting up I'd ignore it.

On the "surging" on start up: Factory air conditioning? If starting with the air (not vent, but air) in any "on" position the engine will high idle for several seconds.

On the seatbelt: As Bill suggested, stamp on the brakes and see if it locks. It probably doesn't, things wear out. I'd replace it, but then again I've spent a few nano seconds pressed firmly against my belt while the sheet metal of the car I was driving was radically altered, in the "open the glove box to view the air cleaner" variety. (I came away with a scratch on the top of my foot.) YMMV.

On Wed, 1 Sep 2004, BikeQuest wrote: [snip]

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Reply to
Lee Ayrton

Since this pan has a plug on it, I dont pull it very often. I use Ultrablack RTV instead of a gasket and it doesnt leak a drop from the pan. KH

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Reply to
Kevin in San Diego

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