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New Comanche owner here. Randomly my headlights, brakelights, dashlights and hazards all stopped working while my blinkers still work fine. Not a fuse or an obvious wire issue and I recently cleaned as many of the grounds as I could find and worked fine after that. Could be a relay? any other similar or common issues with this?

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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, failed emission tests, and wasted money replacing components unnecessarily.

All the components listed below ground at the dipstick tube stud:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the 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. If the whole stud turns, you can use a 7/32″ six point socket or wrench to hold it so the nut can be removed. Worst case, cut the wires and remove the stud and nut. Install new terminal eyelets on the wires when going back together.  Scrape any and all paint from the stud’s mounting surface where the wires will attach. Surfaces 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. Apply a liberal coating of OxGard, which is available at Lowe’s and other stores. Reinstall all the wires to the stud and tighten thdipstick stude 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, apply OxGard, 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 its intended use and subject to corrosion and poor connections at each end.

  • 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. Apply OxGard. 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 with a liberal coating of OxGard.

2 STRONG suggestions regarding the ground system:

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.

For those of us with Comanches, it’s very important to remove the driver’s side tail lamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal.  Add a 10 gauge wire, with an eyelet on each end, from that grounding point to a bolt on the frame. Better yet, on both Cherokees and Comanches, complete Tip 29 for the best fuel pump grounding. Be sure to scrape all mounting points to bare metal and apply OxGard also.Fuel Pump Ground Comanche

If you want to UPGRADE YOUR GROUND AND BATTERY CABLES with custom made parts, contact Paul at www.jeepcables.com 

Neal's cables

Revised 02/04/2017

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CONNECTOR AND RELAY/RECEPTACLE REFRESHING

 

10-pin connector

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.Ballast Resistor

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13 minutes ago, Monte721 said:

 

thanks for the reply, you mean that actual assembly like this? th?id=OIP.Sgwr1yy3N69VqtuE_eIZqAAAAA&pid=Api&P=0&w=227&h=171

Yes, that's what I meant.  However I want to amend what I said - after looking at the wiring diagram, I think you burnt your fusible link that comes off the starter relay.  Consult this portion of the wiring diagram for details:

20210513_001031.jpg.1364c4471e074e9e103a2849bb16fbfb.jpg

 

The fusible link looks like a normal wire, but if blown may be visibly burnt.  These frequently blow because of light switches burning up, however, so make sure you inspect your switch and connector.  It also frequently happens because of corroded front harness connectors that Cruiser referenced above.  Make sure to check both before replacing the fusible link.

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12 hours ago, cruiser54 said:
 

Thank You for the thorough response. I already cleaned the multiple ground connection at dipstick along with replacing the battery cables, that bolt was a bugger. Also replaced main ground as suggested with battery cable (4gage? in pic below). Did not do the fuel pump one (yet), thanks. 

I believe I cleaned some of the electrical connections already and I wouldn't think its the actual lighting connector since they all went out at once at turn signals work but will try to do the electronics cleaner as well tomorrow as suggested just in case. Thanks again 

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19 hours ago, scaleless said:

Yes, that's what I meant.  However I want to amend what I said - after looking at the wiring diagram, I think you burnt your fusible link that comes off the starter relay.  Consult this portion of the wiring diagram for details:

20210513_001031.jpg.1364c4471e074e9e103a2849bb16fbfb.jpg

 

The fusible link looks like a normal wire, but if blown may be visibly burnt.  These frequently blow because of light switches burning up, however, so make sure you inspect your switch and connector.  It also frequently happens because of corroded front harness connectors that Cruiser referenced above.  Make sure to check both before replacing the fusible link.

 

Dug in a bit more today. The fusible link/wires did not look burnt and switch looked intact, I also replaced the relay under the dash but no lights.

 

Then I started cleaning the connectors as mentioned and the front light connector was nasty. The red outer wire broke off and was visibly corroded. It possibly happened when I was trying to remove the connection today or could be the culprit since I was on some pretty bumpy trails this weekend when the lights went out. The inside was very corroded and 4/10 connections broke off. I obviously have to replace it, but since its for the fronts, would that also affect not having brake lights in the rear? 

Also best place to get the replacement?

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I went through just about every other connection as suggested with electrical cleaner and fortunately none looked that bad at all. The only one I did not get to was the complex one up top, I didn't know if there was a trick to opening that up 

 

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Cleaned up these 3 relays by the battery and the contacts didn't look too bad to begin with, are they worth just getting new ones? 
 
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And also found quite a few loose end wires with no obvious connections, 3 or 4 in the engine bay and about 8 under the dash. I have a base model with little options would that be the reason?
 
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I appreciate all the help and insight! 
 
 
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FIrst off, all your pictures seem to be broken.  If you can get those working I can help more.

14 minutes ago, Monte721 said:

but since its for the fronts, would that also affect not having brake lights in the rear?

This is why I suggested checking the fusible link.  It doesn't always look visibly burnt when it goes, though.  The fusible link powers both your front lights, hazards, and stop lights - all the ones you mentioned.  The front harness only connects the front, but also obviously needs to be addressed first. You can quickly check the fusible link by testing continuity between the fat red wire coming off the corroded lighting connector and the starter terminal all the fusible links are connected to.  A good link should only see a few ohms of resistance.

 

6 minutes ago, Monte721 said:

Also best place to get the replacement?

 

I don't know of any source for the OEM connector other than the junkyard.  You can splice in a male/female set of just about any weatherproof connector, though, if you'd like a new one.

 

10 minutes ago, Monte721 said:

Cleaned up these 3 relays by the battery and the contacts didn't look too bad to begin with, are they worth just getting new ones? 

It doesn't hurt to replace them as long as you get quality replacements, but none are related to lighting.

 

Relays.jpg.07c4d2e7249c1d26355a375bfb55f703.jpg

11 minutes ago, Monte721 said:

And also found quite a few loose end wires with no obvious connections, 3 or 4 in the engine bay and about 8 under the dash. I have a base model with little options would that be the reason?

Yes, the dash harness will have all connectors regardless of what accessories are actually installed.  But not the engine bay and lighting harness, to my knowledge.  If I could see your pictures I might be able to help more.

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I'll try the pics again, If you can see the connector its shot, which may take a while to find;

2110797001_lightco.jpg.27b36054b8bea23574b3d8d34f152ad7.jpg1898549507_lightcon.jpg.218822a49e3bf932a0738d6c605b57ac.jpg
 
Good to know how to check the fusible link, thanks for that and the relay diagram, I just cleaned them and will leave for now. 
 
Here are a few more pics of the engine bay wire ends (put duct tape on them) working passenger to drivers side;
- first one looks like its related to blower motor maybe for AC? which I do not have blowire.jpg.22aced13091e4aeb40f2ddfe47ce113b.jpg
 
- round one in the back cluster, no idea backwire.jpg.d763641f63d835a59b495d4d251f637e.jpg
 
- 4 pin near the throttle body, no idea 991856518_tbwire.jpg.328bf6221a3492e1d14d85c09472f41e.jpg
 
- last one near the front headlight connector/air box looks like lighting but looks like they were very clean cuts or factory in case something is added later? ligtwire.jpg.596f3b0b2d3dbe14c8d20679a87bdb6c.jpg
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You have a manual trans? That would explain the empty connector on the TPS near the throttle body.

 

Why not cut the 10 pin connector out and solder the wires together? It serves no purpose except to help build the Jeep on the assembly line. 

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Posted (edited)
4 hours ago, cruiser54 said:

You have a manual trans? That would explain the empty connector on the TPS near the throttle body.

 

Why not cut the 10 pin connector out and solder the wires together? It serves no purpose except to help build the Jeep on the assembly line. 

 

yes manual trans and good idea on the wires, thanks again 

 

Looked at the fusible links and I believe my chinafreight multimeter has a bad wire its not changing from 1ohms so I will have to get a new one. I did notice a cut part of one of the red fusible link wires that could be the lights? but it certainly didnt just fall off so it worked with it like that 

flw.jpg.706a2f57b23d2834c840d04a1286a149.jpg

 

And also got into the ECU? connections and they look bad like coke was spilt in there a dark brown kind sticky residue. Not sure if this is corrosion or some sort of old anti-corrosion gel maybe? I left it for now but what would I even use to clean that up?

cw.jpg.31aeec0c84472314d11e8a41106a2cfa.jpgcw2.jpg.119810efa9210bb6752b65a57c66bc13.jpg

Edited by Monte721
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