aw4 trans problem!

[langer1]

Certainly could cause the shifting problem. The #2 solenoid is engaged for 2nd and 3rd gear, so I would think you'd only have 1st and 4th. I would pull the pan and measure the solenoid directly and make sure it's not a wiring problem. Doesn't explain the code 66 about the Engine Computer not getting messages from the TCU.

Accept he would start it 1st and go stright to 4th, he can't even start it 1st without shifting down manualy just like the TCU is disconnected.

 

[lawsoncl]

Accept he would start it 1st and go stright to 4th, he can't even start it 1st without shifting down manualy just like the TCU is disconnected.

Okay, I think I missed that part. I was just seeing that it was skipping over second and third and the corresponding shift solenoid was reading way hihg resistance. So it is shifting as if the TCU had no solenoid control.

After re-reading the whole thread, I see he has power at the TCU connector and swapping the TCU didn't help. Did you check all of the grounds? Is the TCU well grounded? How about the engine/tranny? With the vehicle parking brake on, engine off, do you see voltage applied to any of the solenoids when you move the shifter?

 

[Runnin'OnEmpty]

Badbowtie, the D7 plug terminal on the TCU is the ground. You can see if there's continuity between it and the body to check the ground wiring. If it's OK, I'd look at the Vehicle Speed Sensor (VSS) as being bad. IIRC, it bolts into the tailshaft area on the driver's side. Also check the wiring to it....

 

[lawsoncl]

A bad output shaft speed sensor will make it stay in first gear as the tranny thinks you aren't moving. On the early AW4s, the sensor is a reed relay that closes once per turn - easy enough to check with an meter and turning the shaft by hand. On the later AW4s (97+ I think) it's a inductive pickup so you can't check it this way, but those also have additional input shaft speed sensor.

 

[badbowtie87]

when i did the check at the TCU terminals it showed that each of the pins that controlled shifting had power as I selected the gear manually, so i know im ok on that end. I also did a continuity check at D7 to a door hinge bolt and it showed that it had a complete ground. I still need to check the solenoid ground that Langer was talking about. i havent been getting home until dark so its been a pain to find time to get this thing figured out.

 

[lawsoncl]

Ok re-reading and sorting out who had what symptoms again (got thrown by someone else chiming in about an error 66). Holler if I missed something badbowtie87.

Symptoms:
In D, it's starting in 3rd or 4th. Shifting manually it goes from 1st to 3rd very quickly and doesn't kickdown under throttle. TCU pins have power and good ground. #2 shift solenoid has a high resistance. You see power at appropriate shifter sense pins when moving the shifter. Swapped TPS, MAP, and TCU. Cleaned NSS.

Can you clarify what it's doing if you put in (1-2). Does it upshift at all or stay in 1st? If the TCU is dead (1-2) should stay in 1st, (3) stay in 3rd, and OD should stay in 4th. If it's upshifting then the TCU is doing something.

Can you check if solenoid #1 is getting power with the ignition on in park. Below is the chart for the solenoids. Solenoid #3 is the torque converter lockup. The solenoids only have a single-wire connector so they get grounded through the tranny chassis. I don't recall if there was a dedicated ground wire from the tranny in the wiring harness (there is one from the speed sensor as I recall). Verify that you have a good ground from the tranny to the body and battery.

Shifter Gear Energized Solenoids
P Park #1-on, #2-off
R Reverse #1-on, #2-off
N Neutral #1-on, #2-off
D First #1-on, #2-off
D Second #1-on, #2-on
D Third #1-off, #2-on
D OD #1-off, #2-off
3 First #1-on, #2-off
3 Second #1-on, #2-on
3 Third #1-off, #2-on
1-2 First #1-on, #2-off
1-2 Second #1-on, #2-on


So regardless of shifter position and the NSS output, you should see #1-on, #2-off when the vehicle is stopped. That high resistance on the #2 solenoid is suspicious.

-Chris

 

[Runnin'OnEmpty]

Badbowtie, I also have a 96, and just looked under it. The VSS/speed sensor is located at the rear of the transfer case, just in front of the driveshaft. One bolt to remove, with a three wire connector. Might be worth a look, since it's so easy to access.

That #2 solenoid resistance seems suspect to me too. Obviously it's not fully shorted or open, but just might be out of spec enough to be sticking closed....?

 

[95XJ Country]

Bowtie I have the same problem going on and I replaced the tcu and still have the same problem. I need to replace my tranny anyway since the person I bought it from has driven it in this condition for over a month before selling it to me. I don't have any faith in the tranny anymore so since I picked one up for $75 and it is in great shape and my transfer case has a hole in it so I am just going to replace them both and hope the problem goes away. If not then it must be a sensor or bad wire. I hope to get to work on it within the next week but I am really busy with work.

 

[badbowtie87]

Lawson, the way you have described my problem is exactly the issue im having. I have replaced all sensors that could cause an issue like this with the exception of the speed sensor. It will not upshift on its own at all. I can shift into second manually but it goes to third immediatly then i shift to 4th and it stays in 4th with no lockup. No downshift at all. Im gonna double check the pins at the TCU terminal one more time and also the speed sensor maybe even just replace the thing. If that doesnt take care of it i will pull the pan and check things out there. It could use a new filter anyways im sure. The guy i bought this jeep from drove it like this for a while and shifted it manually. The fluid is burnt pretty bad so if it ends up needing shift solenoids or something like that i think i will just go ahead and get a used low miliage tranny. Not sure which route im gonna take yet. I will keep posting to let you guys know what i find out.

 

[badbowtie87]

i feel like im leading you guys on a wild goose chase. I rechecked my specs at the TCU plug one more time and came up with some different specs than before. The #3 converter solenoid reads 1.2 ohm. Shift solenoid #2 reads 48milliohms. Shift solenoid #1 reads gives no reading. The TPS voltage input reads .8 volts at closed throttle and 1.9 volts at wide open throttle. The rest seems to be within spec.

 

[lawsoncl]

i feel like im leading you guys on a wild goose chase. I rechecked my specs at the TCU plug one more time and came up with some different specs than before. The #3 converter solenoid reads 1.2 ohm. Shift solenoid #2 reads 48milliohms. Shift solenoid #1 reads gives no reading. The TPS voltage input reads .8 volts at closed throttle and 1.9 volts at wide open throttle. The rest seems to be within spec.

Those numbers sound even stranger. A bad speed sensor will cause it to not upshift out of 1st, but it doesn't explain starting in 4th gear in (D). I can vouch that a bad (or in my case disconnected) speed sensor will start in 1st gear and not upshift in (D).

If it's any help, the solenoids are on the bottom and easily replaced once the pan is off.

 

[langer1]

i feel like im leading you guys on a wild goose chase. I rechecked my specs at the TCU plug one more time and came up with some different specs than before. The #3 converter solenoid reads 1.2 ohm. Shift solenoid #2 reads 48milliohms. Shift solenoid #1 reads gives no reading. The TPS voltage input reads .8 volts at closed throttle and 1.9 volts at wide open throttle. The rest seems to be within spec.

Make sure your meter is working, did you have the connector unplugged?

 

[lawsoncl]

Make sure your meter is working, did you have the connector unplugged?

I'm wondering if his meter even reads milliohms. Most don't go that low. Sounds more like an voltage reading.

 

[badbowtie87]

I had the connector plugged in when it was suppose to be plugged in and unplugged when it specified to be unplugged. I used the chart from Transonline.com
I just assumed the reading was milliohms because it had an M flashing on the screen when i checked it under the ohms setting. Im not that great with multi meters but as far as i know i was doing it right. I am gonna pull the pan this weekend if i get the time. It has to be the solenoids or a ground issue with them. I think it might be best to check the resistance at the plug and then at the solenoids. Maybe this will tell me if its a wiring problem or the solenoids.

 

[langer1]

I had the connector plugged in when it was suppose to be plugged in and unplugged when it specified to be unplugged. I used the chart from Transonline.com
I just assumed the reading was milliohms because it had an M flashing on the screen when i checked it under the ohms setting. Im not that great with multi meters but as far as i know i was doing it right. I am gonna pull the pan this weekend if i get the time. It has to be the solenoids or a ground issue with them. I think it might be best to check the resistance at the plug and then at the solenoids. Maybe this will tell me if its a wiring problem or the solenoids.

If your reading OHMS for the solenoids the connector must be unplugged and readings are from ground.
When ever reading OHMS be sure all voltage is removed or you will blow most meters.

 

[badbowtie87]

Ok, I have one last question and i promise i will stop bugging you guys. I did yet another check at the TCU plug (unplugged). I checked continuity of the solenoid terminals (c14-c15-c16) When i checked through the ground(D7) the only one that had continuity was c14. c15 and c16 had nothing. Am I on to something here or still pissin in the wind.

 

[badbowtie87]

I also forgot to add that i checked the ground wires at the dipstick tube and they all had continuity.

 

[langer1]

Ok, I have one last question and i promise i will stop bugging you guys. I did yet another check at the TCU plug (unplugged). I checked continuity of the solenoid terminals (c14-c15-c16) When i checked through the ground(D7) the only one that had continuity was c14. c15 and c16 had nothing. Am I on to something here or still pissin in the wind.

Check them at the plug on the transmission. I say your on to something because I doubt 2 solenoids would go bad at the same time. Any going bad is rare.
Check the 7 way connector.

 

[lawsoncl]

Ok, I have one last question and i promise i will stop bugging you guys. I did yet another check at the TCU plug (unplugged). I checked continuity of the solenoid terminals (c14-c15-c16) When i checked through the ground(D7) the only one that had continuity was c14. c15 and c16 had nothing. Am I on to something here or still pissin in the wind.

A bad connection for the #1 and #2 solenoids would cause your symptoms. I too doubt that two solenoids have gone bad, so I would start checking the wiring for damage.

Nice picture Langer! My 95 FSM shows the soleniod wire colors in the gray connector are dark-blue with white stripe, violet with white stripe, and white with black stripe. The 99 AW4 I installed in my MJ had black stripes on the wiring instead of white, but the base colors should be the same. Unplug that connector and check the solenoid wires to ground there.

Pins D3 and D7 on the TCU connector both measured zero or less than 0.5 ohms to a grounded point on the body (such as the cig lighter shell)? The M on a meter usually means mega ...

 

[lawsoncl]

Just wanted to reiterate that you should be measuring between c14, c15 and c16 and a ground point on the body - not the D7 ground pin on the connector. (D3 is a sensor ground and not really a true ground either). The solenoids do not have seperate ground wires, but are grounded through the tranny case to the engine and back to the battery.

This is especially true if you undo and measure at the gray connector because the black/tan "ground" wire on the tranny side of the connector only goes to the rear speed sensor and isn't grounded to the tranny. Pin D7 in the TCU connector gets spliced into to a common ground somewhere in the wiring harness between the TCU connector and the gray connector.