cruiser54

How's this? 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: Set your meter to measure Ohms. 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 runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too. If you see more than 1 ohm of resistance, and/or fluctuating 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 03-13-2012

Show them this? Or do it yourself. Renix Jeep C101 Connector Refreshing The C101 connector on 1987 and 1988 Renix Jeeps was a source of electrical resistance when the vehicles were new. So much so that the factory eliminated this connector in the 1989 and 1990 models. The factory recommended cleaning this connector to insure the proper voltage and ground signals between the ECU and the fuel injection sensors. We can only imagine how this connector has become a larger source of voltage loss and increased resistance over a period of almost 25 years. The C101 connector needs to be cleaned at least once in the lifetime of your vehicle. Chances are it’s never been done before. Almost every critical signal between the engine sensors, injectors, and the ECU travel the path through the C101. The C101 is located on the driver’s side firewall above and behind the brake booster. It is held together with a single bolt in it’s center. To get the connectors apart, simply remove the bolt and pull the halves apart. You will find the connector is packed with a black tar like substance which has hardened over time. Take a pocket screwdriver or the like and scrape out all the tar crap you can. Follow up by spraying out both connector halves with brake cleaner and then swabbing out the remainder of the tar. Repeat this procedure until the tar is totally removed. This may require 3 or more repetitions. Wipe out the connectors after spraying with a soft cloth. If you have a small pick or dental tool tweak the female connectors on the one side so they grab the pins on the opposite side a bit tighter. Apply a true dielectric grease, not the stuff that came with your brake pads, to the connection and bolt it back together. Revised 11-29-2011

Does your cluster have the low fuel light in it, or a bulb in that socket? Those low fuel lights usually come on at about 1/8 to 1/16 of a tank.

Brake lights are searching for ground. Remove your left taillamp and check the ground wire. Remove it, scrape the paint off, polish up the terminal and reattach securely. Gotta start somewhere. XJs and MJs all suffered from a poorly and underdesigned ground system. Easy to fix and costs under $20 and an hours time.

So how's it running now? I modified/updated my TPS write-up to include wiggling the harnesses parallel to the valve cover and over near the MAP sensor while checking the resistance in the sensor ground circuit. I've also become aware that there isn't always a group of 3 wires at each crimp but sometimes 2 or 4. Makes no difference how many, just bundle them all together into a bypass harness like you did and it works fine.

You got it!!! Thanks for the replies and photos. I'm hoping this will help others who would like to do this. I think you've proven that diving in and following the instructions will make perfect sense once you open the harness..

So, have you eliminated the other crimp near the MAP sensor and soldered that group of 3 wires to the original 3 you soldered? Pics would be nice.

Correct. Checking and rectifying the sensor ground as needed and outlined in the TPS instructions, along with adjusting the TPS makes a world of difference. The C101 cleaning can cure alot of ills by itself. These are stones not to be left unturned in the diagnostic process.

Get the other crimp removed, remove the single wire between the two and solder the 2 bunches of three wires together. Make sure that the grounds at the dipstick tube stud are removed, cleaned and that the stud is bare metal. That's where the ECU eventually grounds.

Comanchero87, you've got guts!! If you had split open the loom near the MAP you would have found another set of three wires. That set needs to be soldered to the set you already soldered and bypass the C101. But, I'm glad to see that low resistance reading. Have you probed it and wiggled the harness near the MAP since thesoldering job? I updated the instructions to include not only looking for the splices by color code but to expect duct tape over them also. And thanks for the photos.

Cut the crap out between the dotted lines and solder it together. The mod will be very evident once you get the split-loom covering off the harnesses. Any questions, post them up. Thanks Don.

FWIW, if you see higher than 1 ohm of resistance in this circuit, and you have an 87 or 88, you should refresh your C101 connector and then retest. Hornbrod has the hokey diagram and says he will post it. And if anyone wants to improve on my diagram, feel free to do so. But, you should do the mod before doing the diagram.....

How do you know that? I'm curious.

Need 1 ohm or less. Did you wiggle the harness while probing? I just noticed where you live. Fly me over there and I'll do the ground circuit mod for you.

I've got a PDF file of a hand-drawn diagram I made a while back. Anybody able to post it here if I send it to them?

I've done this mod 3 times but it's hard to explain. The CTS, TPS, and IAT grounds come together in a crimp of 3 wires in the harness along the valve cover. Those 3 wires are crimped to a single wire that travels over to the firewall area (through the C101 if you have one). That single wire then crimps into another 3 wires going to the MAP, ECU, and diagnostic connector. There is plenty of wire left to cut out the single wire (bypassing the C101 if you have one), cut the crimps out of each bundle of 3, and solder the 2 bundles of 3 directly together.

I know it sounds confusing to read but that's not it at all. The circuit continues to the ECU and then to the dipstick tube stud. The problem with the crimps is that they are loose many times. The problem with the C101 is that the resistance within it can be high.

First off, do it with the key off. Wiggle the harness along the valve cover and near the MAP sensor while observing the meter reading. You can also check the ground wire at the MAP, IAT, and CTS. All on the same circuit. I did the write-up on this that addresses the poor crimp connections in the harness and also directs the sensor ground circuit around the C101 at the same time. Find your Intake Air Temp sensor. It's the sensor just to the rear of the throttle body, has 2 wires, and screws into the intake manifold. Where it's connector plugs into the harness you will see that one of the wires on the harness side is brown with a white stripe. Follow the brown with white strip wire back into the harness. You'll have to open up the split-loom plastic sheathing to follow it. It will come to a splice with 2 other brown with white wires. They're from the TPS and the CTS. The 3 wires will be spliced to a single wire headed toward the C101 connector if you have an 87 or 88. If you have an 89 or 90, you do not have the C101 bulkhead connector. Now go to the MAP sensor. Follow the brown with white wire into the harness from there. You will find a splice with 2 more brown with white wires. At the splice you will find the 3 wires connected to a single brown with white wire going toward the C101, or just along the firewall towards the engine if you have an 89 or 90. Along with the MAP sensor that you traced, they are the ECU sensor ground port and the diagnostic connector on the passenger inner fender. You now have 2 sets of 3 brown with white wires, one near the firewall and one near the engine. Cut the splices out of each set of wires eliminating not only the crappy factory splices, but also the single wire between them. Bring both sets of 3 wires together. Solder the 2 sets of wires together and insulate them properly with tape or shrink tubing. Zip-tie up your new sensor loom to allow for engine movement. I prefer to cover it with some new split-loom or wrap it neatly with electrical tape when done. Revised 12-02-2011

Unscrew it from the brass looking piece.

Check the TPS on the engine side just to be sure. Only takes 3 minutes.

Why is it cracked in half? Did it contact the frame rail due to bad mounts?

Absolutely. Check your speedo with a GPS. Probably a good idea to keep from getting tickets, too, since you're more than likely going faster than indicated due to the tire size.

What position is the Power/Comfort switch in? It it's in Power, is the indicator light on in the switch?

Remember the old Subaru Brat seats? They had handles!! Probably never find them again.

This tripped the old memory switch bringing back an issue we had at the dealership on an 86 4 banger. The guts of the catalytic converter had melted into a softball sized lump and would blow to the back of the cat and plug the exhaust. Symptoms were backfiring, low power. Then the softball must have rolled around a bit until the exhaust pressure pushed it to the back again. What a bear to find.