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AW4 wont shift

jeepgldgr

NAXJA Forum User
Location
Cincinnati, OH
friend of mine just picked up a 87 XJ 4.0L 231 Aw4 with a lot of issues only has 160,000 on er but is showing all the usual issues I've helped him with a few thank's to the guy's here but now his tranny is acting up I've never had this issue with my waggy so I'll try the guy's on the forum. The tranny will not shift out of 1st after a prolonged drive above 50 mph he'll do some freeway driving then when he exits comes to a stop it sticks in first. I had him try to manually shift it but still does not shift. Now if it sits for a while it shifts again fine??? Any help would be greatly appreciated thank's.
 
I had a similar issue on my '89. Turned out to be a faulty throttle position sensor. A friend who's a ChryCo mechanic found it for me. I would never have thought the two would be related.
 
Question: does it have the original factory fluid in it?

Seriously, the Dex is good for ONLY 30,000 and that is only if it has NEVER been overheated. Each time it has been overheated cuts the service life IN HALF.

So, check the color and smell of the fluid and post up what you find.
 
Shifting characteristics of the AW4 are directly correlated to proper operation of the "throttle position sensor" as already mentioned.

You must rule this very important sensor in or out early in the troubleshooting process. It isn't common, but I have seen this sensor work properly when cold, but be symptomatic when HOT. Testing is recommended, but may not be conclusive if testing a cold engine. Replace it if you are unsure; they aren't that expensive. I recommend using a Mopar sensor here; there is a big difference in engine management sensor quality. Here is more....
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RENIX TPS ADJUSTMENT (87-90)

Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.

IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.

MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have only a flat three-wire TPS mounted on the throttle bodyand it provides data input to the ECU. It has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you
have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over.

Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage.

AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles, as outlined above—FOR ALL ENGINE MANAGEMENT RELATED ISSUES.

However, the automatic TPS also has a square four-wire connector, clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.
FOR AUTOMATIC TRANSMISSION RELATED ISSUES: Check the square four-wire connector side of the TPS.
If you have ENGINE ISSUES check the flat three-wire connector side of the TPS.

For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
 
I agree with Birchlake, but ALL slush box diagnosis starts with the FLUID, followed by checking any adjustments and/or sensors, then determining if the problem is electronic or mechanical.
 
Also check the lines, if they get pinched then it restricts flow causing it to overheat and stop shifting properly, had that happen on my 95
 
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