AW4 probs

i have a odd prob with my aw4. sometimes more often than not i have to manually shift my tranny cause it wont down shift. and if i pull out if i go straight to 4th (OD) it will shift straight there and notgo through the other gears like normal. and other times it will shift on its own but it shifts at like 3500 or somethin. and it wont go to the next gear til it gets to that high of rpm. like ill be goin 45 down the road and it will be reved to like 3000 and wont shift ill have to get up over 50 before it will and if i drop back down to like 40 it will downshift and run at like 3000 rpm maybe a lil less or a lil more. it never slips or anything like that just shifting probs. does anyone have any idea what could eb causein this? or what i can do to find out and how to fix it?

Check out your throttle position sensor (TPS).

the tps will affect the shifting?

Abolutely

lil_red_wagon said:

the tps will affect the shifting?

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Yes. The trans computer looks at the output rpm of the tranny and the throttle position to determine when to shift. The TPS can and does wear out causing shifting problems.

Like lawsoncl said. The TPS has 2 connectors. One feeds the TCU. The TPS is the most likely suspect when you have odd shifting problems. No guarantee that's it, but it's easy to test and simple to replace.

From your profile, you have a 1990. Search the forum for LUNGHD and renix sensor diagnostics.

Also read the "RenX files" thread here.

Could be a blown fuse to the TCU too.

Either way it is not the Tranny mechanical, but electrical, bad TPS or TCU fuse, or a ground problem!!!!

thanx i was lookin into havein it rebuilt. and everyone was tell me 1400 so i was goin to spend 300 on the kit and do it myself. well im glad i dont have to do that i will lok at the fuse. and where could it have a bad ground? would it work to mount one from a ground block to the tranny or somethin? i will look at the tps. i think i am havein probs with it anyways. some times i will start it and it will idle at like 3000 and sometimes normal. and it used to do all kinds of odd stuff with the idle and missin and stuff til i pressure washed the engin bay one day. i know its not a fuse i have already checked that. also could it be the tcu its self?

lil_red_wagon said:

thanx i was lookin into havein it rebuilt. and everyone was tell me 1400 so i was goin to spend 300 on the kit and do it myself. well im glad i dont have to do that i will lok at the fuse. and where could it have a bad ground? would it work to mount one from a ground block to the tranny or somethin? i will look at the tps. i think i am havein probs with it anyways. some times i will start it and it will idle at like 3000 and sometimes normal. and it used to do all kinds of odd stuff with the idle and missin and stuff til i pressure washed the engin bay one day. i know its not a fuse i have already checked that. also could it be the tcu its self?

Click to expand...

TPS hates water!

High idles can also be caused by ground problems. Dirty, high resistance grounds on the TPS connections (there are two different sides to the sensor and 2 different ground wires) tell the ECU and TCU computers your foot is on the gas in error. Lots of good threads here to read up on about this common Renix (87-90 year) problems. Just search and read some old threads first.

Note that the TCU fuse is inline in the wiring about 12" from the TCU, not in the fuse block!!!!!

i was thinkin you where talkin about the transmission fuse thats in the block i didnt know there was a inline one. where is it at? i dont even know where my tcu is. and when is idles up real high and wont drop back down i can turn it off and disconnect the battery and turn it back on and it will idle normal. i didnt realize that the 2 could be connected. i was just wantin to get thetranny prob ixed before i worried about the idle prob.

lil_red_wagon said:

i was thinkin you where talkin about the transmission fuse thats in the block i didnt know there was a inline one. where is it at? i dont even know where my tcu is. and when is idles up real high and wont drop back down i can turn it off and disconnect the battery and turn it back on and it will idle normal. i didnt realize that the 2 could be connected. i was just wantin to get thetranny prob ixed before i worried about the idle prob.

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What year is yours? 1990?

If so the TCU is just under and behind the lower dash on the passenger side.

Electrical issues can cause all sorts of odd companion GREMLINS! Nasty work diagnosing and tracking them down for newbies!

i checked it the fuse is there. im not new with cars just with jeeps. its my first one. and from what i have bein told i got the bastard of the xj's. a 90 limited with a aw4 and a 242. the 242 has bein switched to a 231.

My money is on a bad TPS.

Good Luck

Nick

thanx man my neibor has a parts jeep hould i try that one or just go buy a new one?

By all means try swapping over the TPS from a parts jeep and see what happens. That is assuming its a 87-91? with an auto, so that it has the TPS with the two connectors.

yeah i know its a 4.0 auto and early body style not sure of year

lawsoncl said:

By all means try swapping over the TPS from a parts jeep and see what happens. That is assuming its a 87-91? with an auto, so that it has the TPS with the two connectors.

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Don't you mean 87-90?

While we are on the AW4 topic, I just had to go pick up my daughter due to new AW4 problem the 124,000 mile 89 XJ.

It had been rapidly shifting from 3-4-3-4-3..... at about 35 mph. That was the only issue. Then 2 weeks ago it started a rear drive shaft leak at the rear tranny seal. Fluid was slightly off (burnt orange) in color. I put in a pint of Trans-X 2 weeks ago, and the seal stopped leaking the next day. Had no problems until about 3 days ago when the rapid 3-4-3-4 shifting at 35 mph started. Figured it was just the TPS wearing out. Tonight same problem, but tended to get hung up between shifts and slip for about 1 second between the shift cycling, so I had here drive home in 3rd. By the time she got home it would not shift past 2nd gear in D or 3!

It down shifts from 2nd to first if I manually shift from 3 to 1-2 at about 30 mph. Got up to 45-50 mph in 2nd gear (shifter in 3 and / or D) and it refused to go into 3rd (no more upshift). So it has gotten suddenly worse.

Planning to test the TCU side of the TPS, check the TCU fuse and TPS/TCU grounds, and drain and change out 3 quarts in the morning using the drain plug. Will post test results when I am done.

I am hoping it is just muk in the T fluid (possibly loosened up the Trans-X).

I already tried adjusting the throttle Tranny cable twice a few days ago, but it had no effect.

Don't forget, you can test your TPS voltages and see if you are getting proper in/out V.

You'll need an analog meter to accurately test the function, though.

bigalpha said:

Don't forget, you can test your TPS voltages and see if you are getting proper in/out V.

You'll need an analog meter to accurately test the function, though.

Click to expand...

Thanks, I sorta wrote the latest edition on TPS (Renix) testing, in the RenX Files thread.