1989 Eliminator Posted June 3, 2015 Author Share Posted June 3, 2015 I also found a tcu from a 1998 xj. Different part # Link to comment Share on other sites More sharing options...
shelbyluvv Posted June 3, 2015 Share Posted June 3, 2015 If it has the V6 it is a 84-86 XJ not a 88. No TCU on the 904 trans. Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 3, 2015 Share Posted June 3, 2015 ^^ Si - beat me Bo. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 3, 2015 Author Share Posted June 3, 2015 Well junkyard said an 88 haha well no luck with getting the same tcu. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 3, 2015 Author Share Posted June 3, 2015 Took the board out of my tcu and it looks okay... No blown capacitors or burnt resistors Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 3, 2015 Author Share Posted June 3, 2015 Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 3, 2015 Share Posted June 3, 2015 Did you test your solenoids? Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 3, 2015 Author Share Posted June 3, 2015 So I got a 9v battery with wires attached, I then put the positive wire into the female connector going to the trans in pin F. I then put the negative side of the battery into the female connector going to the trans in pin B. I then put a ohm meter in the same place of the wires and got a open circuit. I did this for E, F, and G and got all open. Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 3, 2015 Share Posted June 3, 2015 Then you are on the wrong ground or the wrong 7-way connector pins. You can't have three open solenoids. This is how my 91 is wired. Check your Electrical FSM to verify your Renix has the same pinouts. Image Not Found Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 3, 2015 Author Share Posted June 3, 2015 Looks like it is the same Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 3, 2015 Author Share Posted June 3, 2015 Should the ground probe on the ohm meter be touching pin B or engine ground? Because when I touch engine ground I get a value and not with pin B This is now with the tcu to trans connector plugged in and back probing the wires... With no voltage: Pin E: 15.2 Pin F: 25.7 Pin G: 15.5 Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 3, 2015 Share Posted June 3, 2015 When the firewall connector is unplugged, it breaks the pin B ground connection, so you're okay. Solenoid 2 (pin F) resistance is too high - should be 15 ohms or less. But usually when the solenoid coil goes bad it opens. I think your best bet is to find another TCU and replace it, then if it's still AFU, replace the solenoids - all three of them. You can also check the solenoid coils via the TCU connector, pins C14, C15, and C16 to ground, with the firewall connector plugged in of course. . Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 4, 2015 Author Share Posted June 4, 2015 Well, let the TCU hunt begin Link to comment Share on other sites More sharing options...
cruiser54 Posted June 4, 2015 Share Posted June 4, 2015 Well, let the TCU hunt begin 87 to 90 with 88 to 90 being preferred. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 8, 2015 Author Share Posted June 8, 2015 Havent found one yet. But... After a day of my TCU being unplugged I decided to plug it back in and see what happens. It NOW shifts from 1st to 4th while the shifter is in D. But, the shift points are way off. In all gears the trans shifts at much higher rpms than normal and sometimes when I let off the gas the truck does not coast, it rather engine brakes until I hit the brake pedal which then settles down the engine. Link to comment Share on other sites More sharing options...
shelbyluvv Posted June 8, 2015 Share Posted June 8, 2015 Check your tps Link to comment Share on other sites More sharing options...
cruiser54 Posted June 8, 2015 Share Posted June 8, 2015 Check your tps Test your TPS on the Trans side. Also be sure the dipstick grounds are perfect. Remove, clean and reinstall. RENIX TPS ADJUSTMENT 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. 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. 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 !! 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. 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 !! Key ON, measure voltage between "A" positive and "D" ground by back-probing the connector. 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 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 12-15-2013 Link to comment Share on other sites More sharing options...
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