Tranny Electrical Issues CLICK HERE!!!!

[Dent Doctor]

Alright guys I have scratched my head long enough, so here is the story. I have a
1998 Cherokee 137,000 miles
6" lift, 35's, and Rhino'd exterior

So the problem I have been having for a long, long time. I have no Overdrive when I run down the road. I have replaced the TPS(Throttle Position Sensor), IACV(Idle Air Control Valve, NSS (Neutral Safety Switch), and TCM (Transmission Computer) and with no avail I still have the problems. I have re-grounded the block, the battery, and 4 wires next to the Computer behind the drivers headlight (not sure if that is the PCM or ECU. Pretty sure it's the ECU but I don't know. So after all that the only way that I CAN get it into overdrive is by driving down the road at around 50mph and turning the key off and back on again. Then for around 1/2 of a mile I can have overdrive. Seeing as how I drive everyday 25 miles one way this isn't a very efficient vehicle without OD. Any suggestions, Comments, or Rants will be greatly appreciated. One more thing I did get the codes pulled. The codes I pulled were:
Eng: 26/P0122 (TPS Voltage Low)
Eng: 137/P0700 (EATX Fault Present) *I read this was linked to TCM

I have looked through the wiring diagram in my Haynes Manual and I do see the TPS and TCM are both connected by a single power wire but there are 3 other sensors connected between them that I would think would pull a code also. I could be wrong though, those three are: Coolant Temp Sensor (temp gauge works), Air Temp Sensor, Heated Oxygen Sensor.

 

[langer1]

Stock gears?

 

[Dent Doctor]

no went to 3.73 when I swapped in the 8.8 that was around the time the problem started.I went from either 3.54 or 3.90 or something the mechanic told me one and the tag on the diff cover told me the other

 

[Dent Doctor]

Anyone have answers for me?!?!?!

 

[langer1]

With 35" your gears are too tall, you should be at least 4.11

 

[lawsoncl]

Eng: 137/P0700 (EATX Fault Present) *I read this was linked to TCM

P0700 means "Transmission Control System Malfunction". Found that it about 10 seconds using Google. Have someone pull the transmission computer info and find out what the problem really is. You've replaced everything but the transmission shift solenoids and speed sensors (there are two, one front and one rear).

Or maybe langer1 is right and you just need to drive faster. :}

 

[Dent Doctor]

Definitally don't need to drive any faster that is not the case at all. Thanks lawsoncl that wil give me something to tinker with. I appreciate your input.

 

[kennzz05]

please let me know what you come up with my 98 also wont engauge the o/d same codes stored in mine too mine is mostly stock though

 

[boise49ers]

I have an 88 that is shifting weird all of a sudden also. It got up to over 3K before it shifted then. I tried to put it in OD and it wouldn't go at all. Then all of a sudden it worked fine. It has been having little episodes like that lately. Where are the shifting solenoids ? Could they just be dirty. I went mudding last week.
Thank for any info, sorry to hijack it just sounds like it is around the same problem.

 

[langer1]

I have an 88 that is shifting weird all of a sudden also. It got up to over 3K before it shifted then. I tried to put it in OD and it wouldn't go at all. Then all of a sudden it worked fine. It has been having little episodes like that lately. Where are the shifting solenoids ? Could they just be dirty. I went mudding last week.
Thank for any info, sorry to hijack it just sounds like it is around the same problem.

They are inside the transmission better hope theres not mud in them. If you got your TPS wet though it could be shot.

 

[Dent Doctor]

Where is this second speed sensor you speak of lawsoncl? I have replaced the one at the transfer case. Also what is the little trick to lining up the NSS when you put it back on? Thanks guys for your help

 

[r6dallastx]

I had the same problem all i did was replace the shift solenoids, very easy to do once the you get the transmission pan off. They are easy to check once you get them off just run some current throught them. Where they connect to the wire harness is + and the body Is - . If the make a click noise they work if they don't they don't work. Here are solenoids on ebay that i found. http://cgi.ebay.com/ebaymotors/ws/e...d=1,1&item=8055252550&sspagename=STRK:MESE:IT

 

[Yucca-Man]

Y'all are overlooking a major red herring in the first couple posts...35" tires and only 3.73 gears? That's a major change in tire size and weight and a negligible change from the factory 3.55s - I'd recommend at least 4.56 in the axles with that size tire.

 

[Dent Doctor]

Thanks r6dallastx I'll give them a test and see. Also how close to my problem was yours? was it doing the exact same thing. i.e. shifting in the other gears and just not the overdrive?

 

[r6dallastx]

well, it wouldn't going into overdirve and it when you put the tranny in D it would just go into 3rd gear. It would only go in first gear when you placed it in 1. It wouldn't never going to OD, but now it works perfect. Overdrive has it own solenoid, and 1-3 work with two solenoids that work with either two on or off or one on and one off.

 

[lawsoncl]

Where is this second speed sensor you speak of lawsoncl? I have replaced the one at the transfer case. Also what is the little trick to lining up the NSS when you put it back on? Thanks guys for your help

In 1997+ AW4 transmissions, there is a front input shaft speed sensor and a rear shaft speed sensor. Pre 1997 only has the rear speed sensor. Both are on the drivers side mid-way up the side of the tranny. The front sensor is almost to the very front edge. The rear sensor is near the back, hiding under the transfer case linkage bracket. Should be able to just follow the wiring.

 

[Dent Doctor]

thanks for your replies guys