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Unread 02-13-2011, 04:19 PM   #1
Gonnabebig
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Join Date: Feb 2011
Location: Amity, Oregon
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Tranny problem!

So I have an 89' Cherokee pioneer. It has an automatic transmission but it's starting out in 3rd gear when I put it in drive so I have to shift manually. I was told it was an electrical problem but I wouldn't know where to start. Can anybody help me?

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Unread 02-13-2011, 05:41 PM   #2
tjwalker
It's the crank sensor!
 
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1999 XJ Cherokee 
 
Join Date: Nov 2007
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The place to start is with the "throttle position sensor". It is the most common electrical failure on the AW4, especially on the 87-90 (renix) vintage. The TPS is directly involved with transmission shifting characteristics.

The first thing you must do is test your throttle position sensor. AND adjust it. Adjustment is necessary on 87-90 and is important.

If everything tests out okay on the TPS, the next stop is the TCU, but the TPS must be verified first.

Here is more....

-------------------------------------------------


RENIX TPS
(Thanks to Joe Peters from NAXJA for this information)

MANUAL TRANSMISSION:

RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS has three wires in the connector. Wire "A" is positive. Wire "D" is ground. Remove the three-wire connector from the TPS. Key ON, measure voltage from "A" positive to "D" ground. Note the voltage reading--this is your REFERENCE voltage. Now, reconnect the three-wire connector to the TPS. Key ON, back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. Adjust the TPS until you have achieved this percentage, if you can't achieve the correct output voltage replace the TPS and start over.

AUTOMATIC TRANSMISSION:

RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES. However, the automatic TPS also has a four-wire connector. For the automatic transmission equipped vehicles the four-wire connector provides data to the TCU. Disconnect the four-wire connector. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Now, reconnect the four-wire connector to the TPS. 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. 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. If you have TRANSMISSION issues check the four-wire connector side of the TPS. If you have ENGINE issues check the 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.
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99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
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Unread 02-13-2011, 05:50 PM   #3
Gonnabebig
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Ok thnx I'll try that and see if it helps any.
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Unread 03-06-2011, 09:59 PM   #4
Gonnabebig
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I finally got around to trying this and it didn't do anything.

89' Cherokee pioneer 4.0litre
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