cruiser54

Is there a such thing as a 'map' of where all the grounds are? Upgrading you mean strip and use a fresh connector I imagine? Here ya go for just the Renix ground refreshing and optional extra cables. Renix Ground Refreshing The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components. The components grounding at the dipstick tube stud are: Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff. The factory was aware of the issues with this ground point and addressed it by suggesting the following: Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint. Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely. While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely. Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end. First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely. Remove the other end of the cable from the rear of the head using a 3’4” socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely. A suggestion regarding the braided cable: I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18” long with a 3/8” lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116. A further improvement to the grounding system can be made using a #4 cable, about 10” long with 3/8” terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115. If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price. Revised 11-28-2011 Do you wanna test the sensor ground circuit for possible bad connections in it, too?

Biggest issues in the C101 is the sensor ground and CPS circuits. I do the sensor ground mod and then bypass the C101 with the CPS wires, clean the C101, tweak the connectors and call it good. Good time to do both actually. The ground refreshing and upgrade, even with only the two cables recommended in my write-up are worthwhile. Even better, but not totally necessary is increasing the size of the pos and neg cables. I agree with soldering and heat shrink vs crimping. That's all I ever consider really. But is there any "value added" benefit to taking the 101 out providing it's been really cleaned and the sensor grounds fix has been done? It sounds like perhaps it would only clean up the look under the hood some but not really offer any other benefit. ???? :dunno: Not really. Getting the CPS wiring around it along with the sensor ground fix would be good though.

Nah. The O2 sensor relay is powered directly by the ignition switch and it was the O2 sensor that shorted. I'd be putting my energy that direction.

Biggest issues in the C101 is the sensor ground and CPS circuits. I do the sensor ground mod and then bypass the C101 with the CPS wires, clean the C101, tweak the connectors and call it good. Good time to do both actually. The ground refreshing and upgrade, even with only the two cables recommended in my write-up are worthwhile. Even better, but not totally necessary is increasing the size of the pos and neg cables.

That's what we were shooting for. No power to pin 30 on oxygen sensor relay. And other places along the way. Glad it's fixed.

The receptacle the O2 sensor heater relay pin # 30 plugs into.

Check where terminal 30 connects to the plug at the O2 sensor relay. Should have power from the ignition switch with the key on. Also check all the fuse links in the orange, green, red, and blue wires from the starter relay.

Perhaps you better inspect the harness that the O2 sensor wires travel through. They could have melted together with some other wires in the harness? Also check the relays on the passenger side inner fender. One of them is for the O2 sensor and perhaps has something to do with power delivery things. If so, that relay may have become damaged from the shorting O2 sensor incident.

There's a harness connector plug behind the driver's side headlight that could be corroded. Also, up high on the driver's side inner fender is the ground for that circuit attached with a screw.

On the driver's side inner fender, near the air cleaner housing is an off-white ceramic ballast resistor with a wire at each end. It could be bad or th ewires are loose fitting/unplugged. Bypass it by connecting both wires together and see what happens.

I had jumped two wires for an EGR valve on the fender well, and miracuously it started after that...I don't quite know what I did to get it to go, because it just suddenly worked. Sure those weren't the ballast resistor wires?

I was there in the early 70s. Am I dating myself?

Under "important note" in the following write-up: 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

Probably not the distributor. The injectors you have should be fine with the heat. Mine are, and I live in Arizona. What happens if you turn the key to ON and let the fuel system prime before turning to START? Have you ever checked your sensor ground circuit for high resistance?

87s came without it but the factory issued a TSB shortly thereafter for a harness including the resistor to eliminate fuel pump noise per customer complaints. They later issued a TSB to put a pulse damper into the hose between the pump and sending unit assembly to further reduce noise. Yes, it is a source of problems. I don't know how many of them actually burn out and fail, but I was surprised to find that the connectors being "wiggly" on the resistor of my wife's XJ were causing symptoms of a bad fuel pump.

I used it on my C101 connector............guess I should clean it out huh? What do you suggest I clean it with? It can't be any worse than the road tar the factory used 25 years ago. If yo really wanna clean it out, use Brake cleaner or electric contact cleaner. Tweak the receptacle pins tighter with a pick before reassembly.

Remember Pismo, too. 67 Bronco with a built 351W and a 4 speed, 4.11 gears, running Gates Commando tires. Gas was 29 cents a gallon.

After reading this and a few others, I'm not sure that leaving the dielectric grease out/off is a good idea, especially in hostile environments. http://www.epinions.com/review/Loctite_ ... 40932?sb=1

I wonder what that crap was that the factory used that left the white hardened residue on the connectors. I will change my write-up if you're absolutley sure of this.

This never hurts and can only help: 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, and adding dielectric grease before plugging it back together. 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 dielectric grease should be added before plugging them back in. I do this on every Renix era Jeep I purchase or work on for someone else. Revised 03/15/2012

The fuel pump ballast resistor's value is about 1.3 ohms. It's bypassed when starting so the fuel pump gets full battery voltage, then is relayed into the FP circuit to lower the voltage to the pump which prolongs it's life and lowers the operating noise. A corroded terminal on the ballast resistor can cause an ohm or two resistance by itself. I think you just lucked out replacing the ballast resistor because by unplugging and replugging the spade connectors you wiped out some corrosion resistance. I hope not, but I think you have a temp fix mate. :cheers: Interesting. My wife complained the other day that her Cherokee was acting like it did just before the fuel pump went out a while back. I did the usual connector checking and found that the connectors at the ballast resistor weren't real tight. I removed them from their plastic housing, squeezed the sides a bit and put them all back together. No more problem.

Aptos, in your avatar. Looks like your sensor ground circuit is good.

Still got the C101 connector on the firewall? BTW, I got one of the worst sunburns in my life on that beach......

It depends which side of the TPS you checked. Did you use instructions that use the flat connector or the square connector. The problem is the TPS has two distinct sides to it. One can be bad, like the engine side, but you're testing the trans side. That's why I wrote the following instructions. CPS will not cause a high idle. 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

Have you ever cleaned your throttle body and IAC? That's where I would start.