Nicolai

have a small issue. with my 88 xj now it feels like she shift to second gear and gets stuck. also first gear or drive it runs really slow. i been told it's the computer. or fuse there all fine

DFlintstone

I read that you can unplug the TCU, (below the glove box), and see if it shifts OK manually. If it does the problem is electrical, not the trans itself. Idk, that is just something I've seen posted a few times. Or maybe just unplugging the fuse there on the harness near the TCU plug will do it.

Do note your TPS is adjustable, affects things and might just be shot or have a wiring problem. See Cruisers tips to check it and it's ground wire.

Nicolai

we just put new tcu and tps it nows runs good thou the shift timing might be off

DFlintstone

Here at > http://cruiser54.com/ TPS stuff is handled:

Cruiser mentions "clearly embossed" on the square (three wire) trans side plug. Myself it took good light and some magnification to find the letters after a few tries. (that might have been a little jab!) I have alligator clips on my meters and use paper clips to back probe. (probe the wire while it is connected). Ether way it's a bit tecky, but important. With your digital meter we can help you through it if you need. (Btw you can unplug the connectors!, but the metering is done with them connected, (except the Jeep side ground could be checked unplugged))

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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. First off, DO NOT UNPLUG THE CONNECTORS!


Cruiser's Mostly Renix Tips
Renix TPS Adjustment

October 30, 2015 salad 16 Comments

Before attempting to adjust your TPS, there are two things that need to be done.

1. 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.
2. With the key OFF, and using the positive (red) lead of your ohmmeter, set on the lowest scale, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself.
3. 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. It is covered in detail in Tip 6.
TPS ADJUSTMENT FOR ENGINE ISSUES
Both Renix manual and automatic transmission equipped XJs and MJs have a flat three-wire connector to the TPS which provides data input to the ECU. The three wires in the connector are clearly embossed with the letters A, B, and C. Wire “A” is positive. Wire “B” is ground. DO NOT UNPLUG THE CONNECTORS!

1. Key ON, measure voltage from “A” positive to “B” ground by back-probing the connectors. Note the voltage reading–this is your REFERENCE voltage.
2. Key ON, back-probe the connector at wires “B” and “C”. Measure the voltage. This is your OUTPUT voltage.
3. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts.
4. 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.
5. 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.
TPS ADJUSTMENT FOR AUTOMATIC TRANSMISSION ISSUES
Renix automatic transmission-equipped XJs and MJs 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 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.
First off, DO NOT UNPLUG THE CONNECTORS!

1. Key ON, measure voltage between “A” positive and “D” ground by back-probing the connector. Note the voltage. This is your REFERENCE voltage.
2. Back-probe the connector at wires “B” and “D”. Measure the voltage. This is your OUTPUT voltage.
3. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts.
4. 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 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. The square 4 wire connector is just not used.
Revised 1-31-2016

DFlintstone

The nature of the thing is to sometimes be a little sluggish to downshift into second I suppose, around 45 mph on a grade? Sometimes I just goose the throttle a little since even a properly adjusted TPS doesn't always agree with what I want. The "power" switch is intended to push that closer...I STILL sometimes goose it to downshift.

cruiser54

Make sure you do Tips 1 through 5.

Jeepin'_Aint_EZ

Everytime I see someone having an issue with a renix jeep, I immediately think "have you done tips 1 through 5?" and I don't even own one

DFlintstone

That's just for 87-88 though. No C-101 connector on 89-90.

cruiser54

Make me a meme?

PNWjeeper

This is what I have in mind, I was thinking James Bond but couldn't find the right look.

Nicolai

we ended up fixing the problem both tps and tcu were bad,

DFlintstone

I would assume he meant "MEANIE". Guess it happens Nicolai. Although the Renix ECU is about bullet-proof, flaws with the TCU's come up. Of course since you changed both the TPS and TCU at the same time, we don't know here though.

Nicolai

well all that matter she's shifting good

DFlintstone

Cool! Done good!