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Slow Shift to 2nd when Cold


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Hey guys,

 

My Comanche (6cyl automatic) is slow to shift to second until I drive for a few minutes and the engine warms up. When I bought it, I immediately had to replace the trans cooler line so I did drain out the old fluid and put new fluid in. The idle is kinda funky as well -- not very smooth.

 

I was told it might be the TPS (the 4-wire one on the throttle body) so I tried to test it using the following procedure:

 

1. Turn the key to on

2. Disconnect the TPS connector

3. Read the voltage between A and D (the reference voltage)

4. Reconnect the TPS connector.

5. Back-probe read the voltage between B and D to see if it's 83-85% of the reference voltage.

 

The problem is, I cannot back-probe the connector after reconnecting it since my leads are just smushing the connector's rubber and not making contact. I tried but the voltage I read through back-probing is 0 (I don't know if this is possible). I'm afraid of re-checking it and destroying the connector.

 

My fluid level at hot, idling in Park is just above the FILL line on the dipstick (it's right at the curvy part of the dipstick) so I don't think the fluid is too full.

 

Long story short, what are some good places to start checking? I've heard solenoids, TPS, fluid level, etc. I really don't want to throw random parts at it.

 

Thanks!

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Here's an easieer way to test the sensor. Check both sides per the instructions just to verify they are good.

 

RENIX TPS ADJUSTMENT

 

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: 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.

If you see more than 1 ohm of resistance 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 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 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. 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 flat 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 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.

 

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. 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.

 

Revised 11-28-2011

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