The Cheap Jeep: $300 1996 Jeep Grand Cherokee 4x4

*sigh*

Well, that could have gone better. Granted, it could have gone worse- it didn't involve flames or tow trucks.

Earlier today I decided that the Jeep should be ready for its first foray out of the driveway and out to run some errands: get some gas (and find out if the fuel level sender is shot or if it was just nearly empty), get it cleaned up (run through the car wash & vacuum it out), grab some tables from my church for SWMBO's yard sale tomorrow, and get some things from the hardware store.

So, everything started off pretty well- drove down to the gas station without incident (though also didn't get up very fast). Had trouble with it grinding when I put it into reverse when I needed to back up at the gas station, but putting it into P and then back into R a few times got it behaving. Put in a few gallons, and headed out. Taking the left I needed to get to the car wash I hit the gas harder than I had yet- and was rewarded with a loud 'thunk' and a LOT of grinding.  Dropped it into N, and then (since I'm sitting in front of a line of cars) into 1 and take off without incident and turn into the car wash a short while up the road. 

Got it washed and vacuumed (it cleans up nice), and had to decide whether I wanted to risk taking it on the next leg or going home and swapping vehicles. Unfortunately, the tables I needed to get would require the Mariner- and I would have needed to empty it out of all of the stuff SWMBO normally has in it for her non-profit's outreach work- so I decided to risk it and carry on.

Made it to the church without incident- and this involved hitting speeds up to 45MPH and it at least shifting from 1-2 and probably 2-3. Loaded up the tables (had trouble getting it into R again...) and headed back out- and then things started to go wrong.

Essentially, it stopped wanting to shift out of first gear- it either wouldn't even try and just stay in first or when it got to where it should have, it would 'thunk' and start grinding gears again. I managed to limp it home keeping it under 25mph- but by the time I got it safely back into the driveway it stank of burnt clutch friction material. -_-

So, now I have to figure out 1) why it suddenly decided to not shift and 2) if its transmission is totally berkleyed as a result of the excursion and having to drive it in just first.

Though the CEL isn't on, the 'Check Gauges' light had been flashing on a lot and making warning 'pings', so I hooked up the code reader and pulled the following codes:

P0713- transmission fluid sensor voltage high & P0711- transmission fluid temp sensor range/performance

And P1763- Governor Pressure Sensor Too High Conditions

So... it looks like several of the sensors in the transmission are bad? If this is the case, it will mean dropping the pan- again. I may be adventurous and try taking it out later with the TCM unhooked and the transmission in 'dumb' mode and see if I can shift it manually. 

Didn't get to do anything further over the weekend... had too much otherwise to do Saturday and yesterday was a generally lazy day. From my reading though it sounds like I will probably need to do something about those sensors. The bad is that it will require dropping the pan (again *sigh*)- and while I can find the governor pressure sensor online I cannot find the temp sensor at all. I've read conflicting reports that it's integrated into the governor sensor (which would make things easy)- but I've also read people swearing that the '96 GC doesn't have a TCM while *looking down at it* between the seats in the Jeep, so I'm not sure what to believe.

The good thing? It occurred to me earlier this morning that I may not need to worry either about the price *or* tracking down the part- because I have a whole other transmission from (supposedly) the same year GC sitting in the garage. Could it also have problem? Likely yes- but at least a) I can more easily pull the pan and inspect the sensors to see if I can find a separate temp sensor and b) I would *hope* that both the same sensors would not have failed on it as well.

Unfortunately probably won't get to it today- with the Jeep finally at least out of the garage for the time being and a few more (non car-related) things gone after the garage sale Saturday I want to take some time to clean up and organize a bit before I pull the Jeep back in for a few days. If all goes well (not betting on it...) and the Riviera gets bought this evening I'll really need the Jeep drivable with how the weather is supposed to be the rest of the week though, so I won't be dawdling too much...

With all off the transmission sensors reading bad, could you have a ground issue? I suppose it's possible that they're all bad, but I'd think about a collective problem between the group of them, either a ground or a common connector. 

mazdeuce said:

With all off the transmission sensors reading bad, could you have a ground issue? I suppose it's possible that they're all bad, but I'd think about a collective problem between the group of them, either a ground or a common connector. 

That's definitely something to check. I've been planning on checking (and cleaning as necessary) the connections on the transmission and seeing what all that does. I wouldn't think that the transmission would have a grounding issue given it's bolted to the engine pretty solidly, but checking the continuity to ground should be easy enough to do.

The "not going  into gear" definitely sounds like the trans problems I had in my old Cougar...just before the trans died an inglorious, quiet, expensive death. Did you add any fluid/additive to it prior to its misbehavior on the streets?

In reply to 4cylndrfury :

I had put a bottle of additive and 2 more quarts of ATF+4.

I'll likely do a bit of 'limp mode' testing this afternoon- once I clean out the garage I'll be pulling the Jeep in to be able to work on it and before doing so will pull it out onto the street and see if I can shift it manually. If it seems to behave itself with the TCM unhooked, I'll be a lot more confident that the problem is something electrical (sensor, solenoid, TCM, wiring/ground) than something actually wrong with the more problematic to repair/replace mechanical parts of the transmission.

I think it mostly depends on whether the sensor grounds through the transmission or if it carries a ground with itself. Also, it doesn't take a whole lot of corrosion to mess with input voltages. 

Having said all that, I've spent stupid amounts of time trying to outsmart problems what were easily solved with parts swapping, so take everything I say with a grain of salt. 

I seem to recall transmissions really don't like having too much or too little fluid.  Electronically controlled ones seem to be better about it, but I'd worry even just a few minutes with an incorrect fluid level could do significant damage.

Spent some time yesterday afternoon cleaning up in the garage and getting (a bit) more organized before pulling the Jeep in (though ironically it will likely have nothing done to it before I pull it back out again, but that's another thread...). Since I was moving it anyway, I decided to do a bit of a test and with the TCM unplugged took it out around the block.

First notable thing: went into reverse without any problem/grinding. Now, it has done that before- but it seems previously it was more likely to do it than not initially. Got out of the driveway and ready to move forward, and put it into 1 and started off- then bumped the shifter up to 2 when it got about to where I figured it should have shifted- and it obligingly bumped up a gear (or two... I've read conflicting answers about what the transmission does when the TCM is unhooked- one says that you can't go into 2nd gear at all and it jumps straight from 1 to 3...). Got up to the stop sign on the main road and dropped it back into 1, pulled out without incident and then back in at the next street and drove back to the house without any problems.

So, preliminarily I'm thinking that the sensors are at least part of the problem- I'll probably do a quick check over the wiring & connections as best I can before I pull the Jeep out from the garage to pull the Riv in this afternoon, and then pick back up trying to resolve it once I'm done with the work on the Riv.

hooray for (possible) problem solving!

In the interest of a thorough diagnostic test, I'd suggest driving it around enough to get the trans hot.

Lots of failed automatics will behave correctly until they get hot, so it would be helpful to know how it acts while hot and dumb, incase it still acts dumb when it gets smart again. 

Crackers said:

In the interest of a thorough diagnostic test, I'd suggest driving it around enough to get the trans hot.

Lots of failed automatics will behave correctly until they get hot, so it would be helpful to know how it acts while hot and dumb, incase it still acts dumb when it gets smart again. 

That's a good point, and something I'd planned on doing- though with some trepidation at getting stuck out with it misbehaving again. Given I'm likely going to be taking what it currently my only safely drivable car offline for a day or two to replace failing wheel bearings, there's a good chance I'll have to use the Jeep and get to see how it does hot...

Looked over the wiring where it attaches to the transmission before moving the Jeep out of the garage, and I can't see any issues with the connections. Granted it's essentially impossible to see the pins on the main (upper) connection with the transmission in its normal installed location.

Once again, while moving the Jeep around with the TCM unplugged I had zero issues with it not wanting to go into gear in 'R' and grinding the gears- it just drops right in and runs perfectly. I tested it a few times as well, putting it back into park and then into reverse- something that previously yielded at least one instance of it grinding. Again, this was all cold- but it has ground in R when cold before as well, so I'm still calling it a good sign.

Not brave enough to take the car in to work, especially since I'm not wholly certain how the transmission is supposed to behave with the TCM disconnected (do I have to shift it full manually? do any gears- like 2nd- not work? etc).

This is an instance where I'd just drive around the block for 20-30 mins, creeping out all my neighbors. 

Short of that, do you have a large tree you can drive up to and leave it in gear? Set the brake and let it get hot then drive around. 

Crackers said:

This is an instance where I'd just drive around the block for 20-30 mins, creeping out all my neighbors. 

Short of that, do you have a large tree you can drive up to and leave it in gear? Set the brake and let it get hot then drive around. 

Given half of my block also works on cars I think they probably wouldn't bat an eye. Unfortunately, the parking brake is pretty much worthless- I need to replace the cables and possibly the pads, and I can't get one of the wheels off to be able to get to the hub on one side.

If the weather continues to be bad this afternoon, there's a good chance I'll risk driving the Jeep the mile or so to the nearest O'Reilly to get the parts I need for the Riv instead of getting soaked on the bike or scooter- that should warm it up reasonably well.

I use a hammer/chisel to remove wheel locks in a similar fashion to the air chisel method mentioned above. 

Takes a heavy hammer (>2#) and a rather committed strike, but it gets the job done. 

Lug lock remover sockets..... They works really well and are pretty cheap....

So a combination of the pouring rain and my being an airhead and having forgotten my wallet when went to work meant that I couldn't stop and get the new axle for the Riv on my way home on the bike, so I had to head back out to get it- and since I would have gotten soaked (again) had I taken the scooter I decided to use the opportunity to test out the Jeep some more so drove it to the parts store and back.

Non-transmission note: it takes more revs than I think it should to get the engine to start- granted I've not replaced anything in the ignition system (plugs included), so I'm not too concerned ATM.

Anyway- once started, went into R without complaint and backed out the driveway, crossed my fingers and put it into D. Drove to the parts store largely without any issues- the transmission actually shifted pretty much as I'd expect it to on the drive there (no roads over 45, so the fact that with the TCM unplugged the transmission shouldn't be able to go into OD didn't worry me; should also not have TC lockup). The only aberrant thing that happened was at the second stop sign I came to- the first one where I had to actually completely stop. When I came to a full stop there was an audible 'thunk' from under the car- presumably from the transmission. Didn't have any problems taking off from that stop sign or at all after the longest stretch of uninterrupted road before making the turn onto the large road and shortly into the parts store parking lot.

The drive back was a bit more interesting as the transmission had unsurprisingly warmed up. First off, it didn't want to go solidly into R without the grinding it's done before... I had to drop it into a forward gear and then back to R before it would click in and work properly. Was a bit worried about it after that- so when I had to stop for a left turn at a light I went to drop it into N and it didn't want to click all the way out and ground very lightly- but stopped when I quickly dropped it back into D. Behaved itself the rest of the drive back home and when I pulled it back into the garage later after finishing the work on the Riv.

So... the transmission seems to behave pretty well when cold, but less so when warmed up. I did check the fluid when I got back home and it was warmed up- was a slight bit over the 'full' mark but not appreciably so. The Jeep is back in the garage for now so I can try and get this figured out. First thing will probably be to pull the pan off the old tranny and take a look at the sensors to get an idea of what they look like.

I may make a thread over in general about this though- honestly I'm a bit clueless about how exactly the transmission works and what the potential problems could be. For starters, if it seems to be behaving pretty much normally with the TCM unplugged, what exactly does it need the TCM for in the first place (yeah, OD & lockup, but still...). And as such, do the sensors that are throwing codes still enter into the equation even with the TCM unplugged? I.e., does the transmission still use input from them in 'limp mode' operation, or does only the TCM care about them? 

The old transmission was also grinding in addition to its other obvious issues right? Have you removed or checked the check valve that's in the feed line to the transmission cooler? It's just forward of the engine block where the hard line ends and the soft lines begin. It's been a while since I've been under a ZJ. It comes to mind because it's the common link between the two transmissions. The check valve is to keep some fluid in the transmission for those folks that hit the starter and slam straight in to gear. You can delete it with a brass fitting pretty easily, I want to say you need a 3/8ths flare and a hose barb on the other end. 

The parts common to both transmission are:

trans cooler and lines

torque converter?

Being a '96 V8 Grand Cherokee you have a 44RE which is basically a 727 Torqueflight with an overdrive added to the end of it. The 42RE behind the 4.0 GC through the 48RE used behind Cummins Turbo Diesels are all related. Without the TCM you are running around with a three speed transmission. The valve body is still hydraulic so the kick down cable is giving the load input to the transmission, as you said the converter lockup and overdrive are electronic. Have you ever dropped the valve body on this junkyard transmission? Usually there is at least one broken accumulator spring that should be replaced. Occasionally that accumulator will get cockeyed in its bore and cause problems. 

Again if transmission 2 is grinding just like transmission 1 I'd start with the check valve to make sure it's not stuck. It's some low hanging fruit since you can check it without jacking the Jeep up. Also check for damage at the harness where the wiring enters the transmission by the shift select rod. 

In reply to bluesideup :

It's a V6 GC, so it should be the 42RE. The TC that came with the 'new' transmission looked to be a in better condition than the one that was on the cracked old one, so I put in with the new one. I did not change out the coolant lines- so that (and the transmission cooler itself) are some of the only physical commonalities between the old and new.

The old one wasn't, to my memory, doing what the new one is- the old one just dragged and wanted to stall the engine out. Once I found the cracked housing I didn't try and move it any more than getting it into the garage to replace it.

I have not dropped the valve body on the transmission- all I did was replace the filter. Automatic transmissions are one of the few things on cars that I'm a bit hesitant to get too much into for fear of totally berkleying something up- they're kind of like black magic to me (honestly, even with reading one of the ATSG service manuals on the 42RE I'm still not wholly certain how the transmission will work with the TCM unhooked since the governor is electronic).

I do have the lines from the new transmission as well (came with them)- I can look at the check valve on them and see if it is stuck and swap it in if it isn't or just use it as a template to put together a replacement delete fitting for it. I'll probably pull the valve body from the old transmission first and get an idea for how everything goes together so I don't risk screwing something up on the new transmission (and I can use it for parts if I need them).

One good thing about the service manual I read was it explained about the governor pressure sensor/trans temp issue: on the newer ones (mine being included) the temp sensor is included in the pressure sensor... so there's one unit that appears to be throwing all of the codes. Granted since I don't think it should be doing anything at the moment with the TCM unhooked and its still not behaving quite right I don't think that just replacing it will solve all my problems- but it may get replaced anyway if/when I have the pan back off.

Unfortunately, I don't know exactly when I'm going to get to doing much on this... in theory tomorrow sometime the Riviera will be heading out and the Rampage arriving, and I'll need to be putting my focus on getting it running and drivable- though if I have time after doing what I need to on the Riv this evening I may look into the check valve situation. Doing some reading, some people have just drilled out the check valve on the stock fitting- and since I have a spare sitting around I could do that and swap it in.

Like you I didn't know much about automatic transmissions until my wallet and tendency to be just smart enough to get myself in to trouble dictated fixing my own 42RE. On mine I lost everything except third gear. It's common in these transmissions to shatter a $5 snap ring in the overdrive unit. For future reference you can replace the overdrive unit separate from the three speed section (torqueflight 727) of the transmission. Pull the transfer case and then the OD unit. I had mine rebuilt by a local shop as it takes a huge press to compress the clutch/stator assembly. You can buy rebuilt units with more clutches on eBay as well. That being said I don't think this is your issue. 

Clearly you aren't getting pressure to the right places in the transmission which is why I thought you might want to look at the check valve. I'll look in my toolbox for the fitting and post a pic. You may also have poorly adjusted bands. When the bands are adjusted too tight the whole unit binds up. Too loose and you have slippage. 

Removing the valve body is not too bad of a job. The solenoids and harness are all together so you can swap those pretty easily. The governor pressure solenoids are known to go bad and cause issues like you're experiencing. Sorry if I'm throwing a lot at you at once but you'll be able to solve it with systematic diagnosis. I'll see if I can find pics from my partial rebuild, I installed the rebuilt OD, replaced all of the electronics inside the trans, and installed a shift kit. 

Theres a great thread over at JeepForum with a full rebuild of an RE. Unfortunately the OP passed away so you can't ask questions but it was invaluable in my garage. 

In reply to bluesideup :

Thanks, I really appreciate the advice and suggestions. The check valve isn't something I would have thought to look at, and is something (given I have another set of lines- the hard portions of which are scrap anyway- on hand) that I can take care of fairly simply. If I really have to dig into the transmission that thread, combined with the service manual I found (http://shop.ukrtrans.biz/wp-content/uploads/catalogs/42RE.pdf) should be quite useful.

What shift kit did you put in yours?

I installed a TransGo TFOD-JR shift kit and tried an upgraded governor pressure solenoid. I honestly can't remember if I still have the upgraded GPS in it. I had a shift issue right after finishing the work which turned out to be mid adjusted bands but I thought it was a leak in my modified GPS block. 

I bought a kit on eBay that included all of the internal trans electronics.

I didn't follow the shift kit instructions exactly. I followed the advice from the JeepForum thread and I'm very happy with the shifting now. The kit firms up the shifts without making the trans in to a tire barker. The higher line pressure makes the trans more responsive as well. The 42RE is never going to be like a DSG trans but it's much better with the kit. I took notes on where I deviated on the shift kit and will look for those as well. The kit includes new acumulator springs and I guarantee. You have at least one broken spring in there. 

I did all of this work on my trans at about 115k. It was well maintained but probably parked without using the parking brake for most of its life. The parking pawl is in the OD unit and it puts pressure on the snap rings. I don't think anyone ever played Wheel of Fortune by slamming it in to park but that doesn't help them either. 

In reply to bluesideup :

Cool, thanks!

The Jeep itself (and presumably the cracked transmission that it came with...) has over 200k on the ODO- I think the used one I got was solidly lower in mileage. I figure when I know I'll be able to get into the transmission that I'll pick up both the new governor solenoid, sensor, & shift kit- but it's likely going to be a while if I want to have any chance of having my own vehicle to drive at the Challenge.

The check valve though is something I can likely take care of very quickly, so I'll do that either this evening or tomorrow morning once I've got things with the Riv finished.