onlyinajeep726 Posted August 23, 2016 Share Posted August 23, 2016 1988 XJ, AW4 with 221k on the clock.Got a little accelerator happy on the old girl this morning in traffic on the way to work and upon arriving to work, noticed it was slipping (seemingly) as I circled around the parking lot. Had a 12 hour shift, so Jeep sat undriven all day. Went to crank and the battery had been drained. Jump started, and put it in (D). Trans acts like the TCM isn't plugged in, slipping is the best way to describe it. If I put it in 1-2, then 3, then overdrive, I can drive it, which is what I did to get home. Noticed on said drive home, it didn't seem like the torque converter ever engaged locked up. I say that because normally there's a slight, but definitive drop in engine RPMs after getting to highway speeds once it's upshifted through all the gears, but that was not the case this time. In addition, I also noticed on the drive home that if I'm not soft on the accelerator, I feel vibration from the floor board. Where's a good place to start? Link to comment Share on other sites More sharing options...
ParadiseMJ Posted August 23, 2016 Share Posted August 23, 2016 Check the level and condition of your tranny fluid. If you're low on fluid, or it's brown/burnt, you need to address that. Check the 10A inline TCU fuse under the passenger knee board. You have to reach up by the heater box and grab the wire harness, pull it down, check the fuse. Check the 7.5 A fuse in the fuse block marked TRANS. If the torque converter isn't engaging...the truck is not going anywhere, as in, not moving at all. It's what makes the tranny GO. The drop in RPM's is overdrive, if the TCU fuse is blown, you have no overdrive. A good place to start is driving a bit more conservatively in your 28 year old truck with 221 miles on it...then address the fluid issue before you blow it up. You asked, just sayin' Good luck. :cheers: Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 23, 2016 Share Posted August 23, 2016 I'd say a good place to start for the vibe is to take a peek at the transmission and motor mounts. Link to comment Share on other sites More sharing options...
Eagle Posted August 23, 2016 Share Posted August 23, 2016 Check the level and condition of your tranny fluid. If you're low on fluid, or it's brown/burnt, you need to address that. Check the 10A inline TCU fuse under the passenger knee board. You have to reach up by the heater box and grab the wire harness, pull it down, check the fuse. Check the 7.5 A fuse in the fuse block marked TRANS. If the torque converter isn't engaging...the truck is not going anywhere, as in, not moving at all. It's what makes the tranny GO. The drop in RPM's is overdrive, if the TCU fuse is blown, you have no overdrive. A good place to start is driving a bit more conservatively in your 28 year old truck with 221 miles on it...then address the fluid issue before you blow it up. You asked, just sayin' Good luck. :cheers: The above is incorrect. The truck will drive with the torque converter not locking. The behavior described is exactly what will occur if the TCU isn't functioning, and the FSM test procedure tor TCU problems is is to pull the fuse and shift manually. Slipping is what an automatic transmission does -- the torque converter lockup is to eliminate the slippage at road speed. Do follow the advice to check the fuses. If the transmission drives the vehicle and shifts manually, it doesn't sound like a mechanical problem, it sounds like an electrical (or electronic) problem. With luck, it'll be one of the fuses. Otherwise, you may be looking for a TCU. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted August 23, 2016 Share Posted August 23, 2016 He said he thought his torque converter wasn't engaging not that it wasn't locking up. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 23, 2016 Share Posted August 23, 2016 Check the TCM fuse. Link to comment Share on other sites More sharing options...
Eagle Posted August 23, 2016 Share Posted August 23, 2016 He said he thought his torque converter wasn't engaging not that it wasn't locking up. I understand that. But the vehicle drives so the torque converter obvious IS engaging. There's no way for it to NOT be "engaged," since there is no mechanism to "engage" or "disengage" it. And fourth gear is not disabled if the TCU doesn't work. The torque converter lock-up is disabled, but the 'D' position on the shifter is fourth gear, and you can manually shift into fourth. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted August 24, 2016 Share Posted August 24, 2016 1988 XJ, AW4 with 221k on the clock. Noticed on said drive home, it didn't seem like the torque converter ever engaged. Where's a good place to start? Check the level and condition of your tranny fluid. If you're low on fluid, or it's brown/burnt, you need to address that. Check the 10A inline TCU fuse under the passenger knee board. You have to reach up by the heater box and grab the wire harness, pull it down, check the fuse. Check the 7.5 A fuse in the fuse block marked TRANS. If the torque converter isn't engaging...the truck is not going anywhere, as in, not moving at all. It's what makes the tranny GO. The drop in RPM's is overdrive, if the TCU fuse is blown, you have no overdrive. He said he thought his torque converter wasn't engaging not that it wasn't locking up. I understand that. But the vehicle drives so the torque converter obvious IS engaging. There's no way for it to NOT be "engaged," since there is no mechanism to "engage" or "disengage" it. Unless it's broken The OP said he thought the torque converter was not engaging...I said basically it IS engaging because otherwise it would not go , which it is. (so he could rule that out) A torque converter that was broken might not engage. My first thought was to check the fluid and the fuses. The OP made it sound like he did not know the difference between engaging and locking. So, sorry, I'm done. I'll try to be more accurate the next time. Hope the OP works it out Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted August 24, 2016 Author Share Posted August 24, 2016 No need to argue, guys. My mistake on the incorrect terminology (I'll edit my original inquiry to eliminate any confusion). I should have specified that after getting up to speeds of around 45-50, the RPMs normally drop slightly, and that is where the torque convertor usually locks up, but that is not present at this moment.A few additional things I'd like to specify, as well as things I want to note that I've looked at or that have been changed recently: I looked over both the 7.5 & 10 amp fuses, and both are fine. I haven't swapped out the TCM yet, but that will likely be next.I would also like to note that the TPS has recently been changed out for a brand new one. I've been rock crawling and drove it 2.5 hours home without issue, but that's not to say that it could or couldn't be an issue, in part anyway. Also, I recently upgraded to a 1990 ECU (made for a manual transmission) thanks to Cruiser54. I don't suspect that has anything to do with the problem, as I'm under the assumption that the ECU doesn't communicate with the TCM on anything before 1997, but if that is an incorrect assumption for any reason, please do enlighten me.Another area of concern is that the battery keeps dying when it's parked for a while. This was not an issue prior. I suppose it could be coincidental, but I have my doubts. Finally, to answer the suggestion of motor and trans. mounts... I'm running Brown Dog poly MMs, but the trans. is the original. No vibration issue prior to this incident, either. Also, the fluid is at the correct level, as it always is. I'm particularly anal about keeping fluids in check. Might be good to change it out, as it's not as ruby red as fresh fluid, but no burnt smell is present that I've noticed.As suggested, I will be a little softer on the accelerator from now on... After all, it's not drag car lol. That 4.6L is too tempting sometimes, though. Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 24, 2016 Share Posted August 24, 2016 There are three solenoids in the AW4; solenoid #3 is the one for TC lockup. Check the solenoid #3 coil resistance with an ohmmeter at the 7-pin connector on the cable that runs from the TCU to the AW4 behind the engine; it should be a white or light gray connector. The resistance should be 12 - 15 ohms. Connector Pin Layout E F G H C B A Solenoid 1, B to GSolenoid 2, B to FSolenoid 3, B to E Link to comment Share on other sites More sharing options...
cruiser54 Posted August 24, 2016 Share Posted August 24, 2016 Here's a thought. Are the brake lights staying on and the TC not locking due to an issue with the switches at the brake pedal?????? Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 25, 2016 Share Posted August 25, 2016 I doubt it. While in DRIVE, the TC receives the lock signal from the tranny speed sensor, and unlock signal from the NO set of contacts on the brake switch. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 25, 2016 Share Posted August 25, 2016 But, if the white TCC switch up by the brake pedal is misadjusted, the converter will never lock up. Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 25, 2016 Share Posted August 25, 2016 That's Renix I guess; the HO brake switch is entirely different. The HO brake switch has three sets of contacts; brake lights, TC unlock, and cruise. Anyhow, the OP should check the #3 solenoid coil first to make sure it's not open. Or the TC will never lock up. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 25, 2016 Share Posted August 25, 2016 Or look here: Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted August 28, 2016 Author Share Posted August 28, 2016 There are three solenoids in the AW4; solenoid #3 is the one for TC lockup. Check the solenoid #3 coil resistance with an ohmmeter at the 7-pin connector on the cable that runs from the TCU to the AW4 behind the engine; it should be a white or light gray connector. The resistance should be 12 - 15 ohms. Connector Pin Layout E F G H C B A Solenoid 1, B to G Solenoid 2, B to F Solenoid 3, B to E I will check that as soon as I'm able to do so. I do have a question pertaining to this, though. If #3 solenoid is bad, or otherwise acting up, would that be the cause to all of the issues that I initially, and later, listed? Or would it only pertain to the final lock up after reaching highway speeds? Here's a thought. Are the brake lights staying on and the TC not locking due to an issue with the switches at the brake pedal?????? Negative, Pete. That was never an issue prior, nor after this unfortunate incident. But, if the white TCC switch up by the brake pedal is misadjusted, the converter will never lock up. It's in good working order. TC lock up was consistent around the 45-48 mph mark, dependent of course on normal, smooth acceleration. Link to comment Share on other sites More sharing options...
HOrnbrod Posted August 28, 2016 Share Posted August 28, 2016 I will check that as soon as I'm able to do so. I do have a question pertaining to this, though. If #3 solenoid is bad, or otherwise acting up, would that be the cause to all of the issues that I initially, and later, listed? Or would it only pertain to the final lock up after reaching highway speeds? All the issues you had/have? No. If the solenoid is gone (open), you will never have TC lockup or OD except by manually shifting. If it's intermittent, going bad and opening/closing, it will cause erratic shifting issues all across the board in D. It only takes a minute to check the coils of all three solenoids to verify coil continuity. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted August 30, 2016 Author Share Posted August 30, 2016 So, I've been relatively busy with work over the past few days. I've had the battery on a trickle charger for several days and the battery is fully charged. I decided to take it out on a test drive around the block. It shifts fine, just as it did before. BUT... I noticed that the volt meter in the instrument cluster is showing just over the lower red mark (10 volts, give or take). Perhaps I killed the alternator in the initial incident, didn't notice the volt meter, and the continued drive to work sucked the battery voltage down? Is that something that would cause the trans. to act like I experienced?My hypothesis is such a demand on the electrical system caused wonky shifting since the trans. requires a certain amount of voltage/current to activate the solenoids? Does that sound right?I'm still going to check the resistance/ohms of each solenoid just to be sure. Now, in addition, I'll be having the alternator tested at the local posts store. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted September 2, 2016 Author Share Posted September 2, 2016 Anyone? Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 2, 2016 Share Posted September 2, 2016 Although the volt gauge reads around 10 volts , it may be inaccurate and you may need to check the volts at the battery posts , TCM etc with a multimeter . I can't comment on if it's causing your symptoms ... Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted September 2, 2016 Author Share Posted September 2, 2016 What I can say is that the alternator is definitely messed up. It is squealing because the back ball bearing has pretty much fallen apart and lost most of it's balls and the retaining ring. I suspect the sudden increase in torque from flooring it put a little more stress on the shaft, and exacerbated the issue. I should have a new alternator tomorrow, so I will install it and report back. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted September 3, 2016 Author Share Posted September 3, 2016 Well, the alternator did the trick... Still don't know how or why. Link to comment Share on other sites More sharing options...
Billy Posted September 3, 2016 Share Posted September 3, 2016 "Also, I recently upgraded to a 1990 ECU (made for a manual transmission) thanks to Cruiser54." Obviously it's Cruser54's fault. Take back his free magnet and ban. This was out of my league but learned a lot from this post. You ever check the #3 solenoid just curious? Link to comment Share on other sites More sharing options...
cruiser54 Posted September 3, 2016 Share Posted September 3, 2016 Well, your alternator didn't have enough balls to charge your battery . Link to comment Share on other sites More sharing options...
schardein Posted September 3, 2016 Share Posted September 3, 2016 Well, your alternator didn't have enough balls to charge your battery . :rotf: Link to comment Share on other sites More sharing options...
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