89CherokeePioneer
NAXJA Forum User
- Location
- Massachusetts
I'll disconnect mine and go for a spin later and let you know. It should probably still shift, since it would still see speed, but firmness and shift timing would likely be compromised.
btam13 said:When you unplug the TCU pigtail of the TPS, should the trans be able to be shifted through the gears manually? If so, at what RPM would the trans shift at? I tried this on mine but only took the RPMs up to 3000 and then tried to shift it manually. No shift happened. Thought this might isolate the problem to the TPS for confirmation.
Ecomike said:If you disconnect the TCU, it will shift manually using the shifter. IN 1-2 it needs to get up over 4,000 or 4,500 rpm to shift to 2nd, but it will shift in 3rd earlier if you shift from 1-2 to 3 manually.
I it does not shift manually as you go from 1-2 to 3 and then to 4, with the TCU disconnected, you have AW4 problems internally.
No, it is best to test the TPS ground wires to the battery negative post, power off, with ohm meter first. If either is more than 1 ohm, you have a bad ground. Find the bad ground connection and fix it, or run an extra ground wire from the bad TPS ground wire to the battery negative post. Once you have verified that the ground wires are less than 1 ohm to the negative battery post, then and only then do you calibrate the TPS. Then it won't matter where you conect the meter ground. Fixing a bad ground wire will change the TPS readings, and the calibration, that is why the grounds should be checked and fixed if needed first, before doing the calibration.btam13 said:I think that the TPS is shot. Last night I used a volt meter to test the input voltage to the TPS on the TCU pigtail and got about 4.8 volts. I then checked the output voltage and got nothing. Zero! Had to put the TPS back the jeep since I already took it off thinking I could bench test it. Now, I'm not completely confident that I tested it right but I believe I did. Have to pick up the new TPS after work. Is it better to test input and output voltage using the battery negative post as the ground?
btam13 said:I didn't let the RPMs get that high before I figured it wasn't going to shift and stopped trying I let it get to 3000 RPMs with no notice of a shift from 1st to 2nd and then tried to manually shift to 3rd with no notice of a shift. Should I try again and let the RPMs get higher just to rule out AW4 internal problems?
Ecomike said:No, it is best to test the TPS ground wires to the battery negative post, power off, with ohm meter first. If either is more than 1 ohm, you have a bad ground. Find the bad ground connection and fix it, or run an extra ground wire from the bad TPS ground wire to the battery negative post. Once you have verified that the ground wires are less than 1 ohm to the negative battery post, then and only then do you calibrate the TPS. Then it won't matter where you conect the meter ground. Fixing a bad ground wire will change the TPS readings, and the calibration, that is why the grounds should be checked and fixed if needed first, before doing the calibration.
If it completely refuses to shift into a higher gear while in 3rd on the shifter, than I would say you have a transmission problem too, or a shift linkage problem.
btam13 said:I wouldn't imagine an internal transmission or shift linkage problem would manifest itself just from degreasing the engine. I think I am going to concentrate on the grounds and a new TPS after work and see where that takes it. Oh, and I am definately adding a ground from the TCU pigtail on the new TPS just for good measure.
Ecomike said:Well I don't know if the manual shift valve is different, or entirely seperate from the solenoid activated shift valve. It they are seperate circuits, I guess it is possible for the manual shift valve to die, and the electric actuated shift valves to work once the TPS is fixed. But I don't know the entire layout of the valve body, so I am not sure. I have been told repeatly, that if it shifts manually and not automaticaly, the AW4 is OK and the TPS is bad (in general anyway).
btam13 said:Are we talking about the whole 3 key cycles thing?
It should be shifting out of first at redline at WOT.btam13 said:2500 to 3000 RPMs at WOT.
Ecomike said:No, just disconnect the battery for an hour to clear the old sensor memory data in the computers, then reconnect and give it a good drive. That should fix the low idle.
The ECU and TCU sides of the TPS have diffent ground wires. If you want just run one fron the battery to the TPS, then split it into a y to both sides of the TPS's ground wires at the harness side.
89CherokeePioneer said:It should be shifting out of first at redline at WOT.
Also, I did go to see how mine acted with no TCM TPS connection and it isn't starting now.
I think I pissed it off.