JeepComanche89 Posted January 7, 2013 Share Posted January 7, 2013 I have a 1987 jeep comanche that originally came with a 4.0, ba-10, and was 2wd. I swapped in a newer 4.0 and front and rear axles from a donor. The donor is a 1989 comanche, with a automatic trans originally mated to the 4.0 that I swapped into the 87. Instead of swapping in the auto trans from the donr, I got a ax-15 from a 95 cherokee. I just replaced the tps with one for a manual trans, which lowered my rpms for the better. however now my tach has stopped working. My gauge cluster is from the 89 donor since it has the correct milage. The tach worked fine before i changed the tps. Could this be my problem? Link to comment Share on other sites More sharing options...
Eagle Posted January 7, 2013 Share Posted January 7, 2013 I don't see how the TPS could kill the tachometer, and I also don't see how changing the TPS could lower your RPMs. Especially with a manual transmission, your RPMs are directly related to gear ratio, tire size, and road speed. The TPS has NOTHING to do with it. It CANNOT affect your RPMs at any given road speed. Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 7, 2013 Share Posted January 7, 2013 I think he's referring the RPM at idle. I just replaced the tps with one for a manual trans, which lowered my rpms for the better. however now my tach has stopped working. My gauge cluster is from the 89 donor since it has the correct milage. The tach worked fine before i changed the tps. Could this be my problem? The new TPS should not stop your tach from working; I think it's coincidence. Stick the old TPS back in and try just to be sure. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 7, 2013 Share Posted January 7, 2013 The TPS is not adjusted correctly then. Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 8, 2013 Author Share Posted January 8, 2013 Sorry about that, Yes I'm referring to the rpm's at idle. If its not the tps, what do you think it could just make the tach suddenly stop working? Link to comment Share on other sites More sharing options...
cruiser54 Posted January 8, 2013 Share Posted January 8, 2013 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: 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 body and 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. Revised 09-22-2012 First off, you need to adjust the TPS to get it to idle properly. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 8, 2013 Share Posted January 8, 2013 Tach signal comes from the ICU underneath the coil. Check the connection. Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 8, 2013 Author Share Posted January 8, 2013 thanks, ill look into the ICU as soon as i can Link to comment Share on other sites More sharing options...
Biotex Posted January 8, 2013 Share Posted January 8, 2013 Tach signal comes from the ICU underneath the coil. Check the connection. Here is a diagram that may help you. Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 8, 2013 Author Share Posted January 8, 2013 Sweet, thanks. Ill take a look tomorrow and see what I come up with Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 20, 2013 Author Share Posted January 20, 2013 Tach started working today, didnt do anything but clean the relays. I don't know but its working and thats a good thing. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 20, 2013 Share Posted January 20, 2013 Here's something to do in your spare time: I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight. ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else. Revised 07/23/2012 Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 20, 2013 Author Share Posted January 20, 2013 Yes, you mentioned doing this before. All the connectors are greased with dielectric grease, and I think I have all grounds cleaned real good then grounded. But is there more then one ground on the dash itself? I have the one on the drivers side mounted to the bottom of the dash, will probably relocate to the body as I read through one of your writeups. Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 27, 2013 Author Share Posted January 27, 2013 Cruiser, you mention being able to use a auto trans tps in place of a manual. If I adjust my current manual one, then decide I need to replace it, will I have to readjust it if I replace it with a manual? I'm sorry for all theprobably stupid questions but this is new to me. Also what would cause a surge, a bad TPS, or IAC? And what would should stock idle speed be, The only "performance" mod I have is a pacesetter header lol Link to comment Share on other sites More sharing options...
88mjgilley Posted January 30, 2013 Share Posted January 30, 2013 the only reason why people run the auto tps is price they are 1/2 the price of the manual one but also any time you loosen a screw on eh tps you need to check to make sure that it is still set correctly Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 30, 2013 Author Share Posted January 30, 2013 the only reason why people run the auto tps is price they are 1/2 the price of the manual one but also any time you loosen a screw on eh tps you need to check to make sure that it is still set correctly Link to comment Share on other sites More sharing options...
JeepComanche89 Posted January 30, 2013 Author Share Posted January 30, 2013 This makes alot of sense, i replaced the tps with one from a maunual. This could be why its bot adjusted correctly. I will have to try and readjust it according to cruisers tips Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now