91Pioneer

I thought I'd post a followup in case it helps someone down the road. I wound up taking my accelerator cable off and seeing if it could be glued or fixed but the plastic was brittle and kept breaking. I wound up buying a new ATP Y-296 cable and it fit and works perfectly. I had got another one from the junkyard but it was too short. For my 89 MJ 4.0, you want the slightly longer version of the cable. If you have this issue, measure yours before buying.

My fuse is melted and the power side of the fuse connector is broken off (just the one side that feeds the blower still exists) so I was thinking I need to put a relay between the fuse wire and the blower motor but there are connections there, fan switch, and the resistor thing. I wonder if I can just put it just after the fuse somehow?? I'm not too sure, I was just thinking someone must have done this already so I was trying to to reinvent the wheel so to speak.

I know how to wire one relay, I'm trying to figure out like do I need to wire 4 relays or 1 relay and where in the circuit does it go? I don't understand because of the different speeds I don't think a single relay would work with reduced voltage on lower speeds??

Neat idea! Looks like a good design to me.

Bump.

I added "factory" DRLs to my US-spec MJ and added the aftermarket headlight relays. Project is done the only odd thing is the DRL output is just under 2V per headlight, they seem a bit dim but as long as it passes inspection I don't care.

Thanks, your help has been invaluable in this and other wiring threads. Pic just for fun.

When I say ignition wire I mean the "turn on" wire for the DRL relay, it's yellow. I put it to the yellow wire in the big loom, must be the one you mention. Does that seem like an issue? Yes it should go back to the ignition switch but the draw should be minimal. The actual power draw wire for the DRL relay goes to the fog lamp power wire (10-pin harness) because if the headlights are on the DRLs are off so I'm kind of "power splitting" in a sense. The DRLs power the high beams at 50% voltage. And, the aftermarket HI/LO relay power wires are run to that red wire I discussed, that "main" load runs back to the starter relay as we discussed. The "turn on" signal for the high and low beams tap into the 10-pin harness. As far as I can tell the load is coming from the right places....??

Well I found one eyelet at the starter terminal that affected the headlights but it had two wires attached. So long story short 3 wires in that bundle had continuity with the eyelet so I would up guessing which one was the D1 wire at the back of the fuse box on the engine side and tracing that wire back and soldered / tapped into it. I then tapped the ignition wire into the yellow wire in that loom there too that runs along the driver fender well. I did not test yet but I think it's good to go, fingers crossed. I need to replace the washer pump as it is leaking, before I put everything back together.

Thanks I'll see what I can find out tomorrow. 4 of 7 links are green so that's already narrowed down a bit. I would bet the headlight wire at the relay goes straight to the wiring harness and along the way as opposed to going into another connector nearby.

Does your diagrams say how many and what gauge of red wires are passing through that harness? I wonder if the headlight wire feed is thicker than the others due to the load of the lights versus things like the radio, gauges, etc. I am not near the truck anymore but now I wonder if there are different sizes of red wires.

Whoa, thanks for the idea. Yeah, I guess one of those wires would go to the headlight switch normally! That is smart thinking right there. Do you know if fusible link J goes to the starter relay terminal? I suppose I could disconnect those one at a time to see when the headlight switch stops getting power?? I wonder if I could get away without a fuse then for the new headlight relays since it's already protected by the link. Hmm...

I need to tap 12V battery power, I have exposed the main harness behind the driver headlight. Is it smart or dumb to splice into there to get 12V battery power to power my aftermarket headlight relays? I will of course put a fuse inline. I *could* run a wire back to the starter relay terminal that has battery power but that seems almost pointless when I can tap into it right here. I see no reason why not if the splice is done properly. There are a few red wires, I would splice into the thickest one.

That power wire is for fog lights, and as you can see, the red wire doesn't continue in the harness on the other side. You can just electrical tape that wire up and ignore it. Pull the connector apart, there will be corrosion in there. Clean it up with DeOXIT see https://cruiser54.com/?p=35 The instrument lights are not related to this plug, that's a separate issue. Go check your instrument panel ground https://cruiser54.com/?p=110

I don't know what the park brake DRL wire is looking for, ground or power? I'm afraid to just put power to it or put it to ground as I don't want to fry it, I desperately need it to work for the safety inspection (the DRL function, not the OFF feature). The park brake wire has a diode in it, I think it's called. It had not occurred to me that the DRL should be off during cranking

An update -- so I got the wiring soldered up (mostly). I am using the dual aftermarket relays to handle powering the headlights, and I wired up a factory DRL relay from a '90 CDN XJ. By using @gogmorgo's tip of putting the DRL output wires on the other side of the relays the high beam indicator works as the factory intended without me needing to wire up the high beam DRL wire. I ran into a few snags during testing like a bad relay out of the box and a bad connection at the headlight, but now I'm ready to tidy up the wiring and actually install it in the truck. Here's a pic of the T-harness that I created. I am drawing ignition power from the main wire bundle going past, I am grabbing battery power direct from the starter relay for the 2 headlight harnesses, and the DRL relay gets power from the 10-pin harness power wire. Grounds will go to the existing bolt on the inner fender by the washer bottle. So far so good. One thing I'm left wondering is how to hook up that park brake wire that turns off DRLs when the park brake is engaged. I was looking at the wiring diagram and it *appears* that I can tap that wire into the grey/black wire at the proportioning valve and that may work. Otherwise I will have to run that wire all the way into the cab at the park brake somehow. That part of the wiring is unclear to me still. Just for reference the wiring on the right side of this pic goes inline at the 10 pin headlight harness.

Thanks. I did some wiring today, made some great progress. I'm being super picky so it's taking a long time LOL I'm trying to make it look pretty darn factory.

That's exactly the problem, the 18 looks like 14. I'm going to run a new wire back to the diagnostic port and tap ignition there, not a big deal since I plan on running a wire for battery power anyway.

Ah crap, the cheap headlight harness has 18awg wire, stock is 16 ga. Shoot, I'm gonna DIY some of my own stuff instead of downgrading my wiring. Beware the cheap headlight harnesses that don't give specs.

Is there a good place to tap an ignition-on wire near the LF headlight area? I think I may run the wire back to the Renix diagnostic connector, I see one of those is ignition on and I don't use that connector anyway.

@gogmorgo I don't know if you'll see this in time, but I'm wiring my T-tap 10-pin harness. Technically tonight I'm planning it and hopefully tomorrow starting cutting and soldering. Today I de-pinned the 2 extra 10-pin harnesses and discovered one is unusable (broken). Anywho.... My thoughts are this. I will make a male/female "T" wire harness that goes at the stock 10-pin harness location. The following wires will go straight through with no modification: - grey-black left signal - brown right signal - dark blue park lights - green/black fog My plan for the remaining wires is as follows: - white high beam - cut the wire, redirect this to the HI beam signal "upgraded" new headlight relay - light green low beam - cut the wire, redirect this to the LO beam signal "upgraded" new headlight relay - black ground - this will pass through the harness but I will also use this ground point for the DRL relay but not new headlight relay pair - 12V battery - this will pass through as it's only used for fog lights, but I will also tap it directly to power the DRL relay, I think this is OK because when the DRL relay is drawing power for high beams at half voltage, there is no way the fog lights can be on (they can only be on when the low beams are on) so I think the power draw is totally fine here. - use all new wires to the headlights themselves, leaving the old stock wires in the old harness just tucked out of the way (unused, unpowered) - the DRL HI and LO beam wires will tap into the headlight wires AFTER the relays Then, for the two new headlight relays I will: - the signal/trigger wires are the white and light green from the 10-pin T-harness - the grounds will get tied together and ran back as a new eyelet on the ground by the washer jug (mid-point driver inner fender) - the main power for these I will run a new wire all the way back to the battery starter relay point with the existing 40A fuse that feeds both relays I don't plan on hooking up the DRL headlight indicator wire unless required and likely not the park brake wire at this time. If I can test the park brake wire I will hook that up though so I can click the park brake on a notch or two to disable DRLs in the rare case I need to do so. If you have any suggestions or thoughts please let me know.

Thanks, Ohm.

Yes, C102 connector, pin #6. Where is the fusible link located? Is it connected to the starter relay beside the battery? I noticed some wires coming off there. And do you know the capacity of the stock fusible link?

I have the header panel off my front end to hardwire DRLs and put the replacement "upgrade" headlight harness in. So there is 12V battery power at the red wire on the 10 pin harness. I am struggling a bit with the wiring diagram. Does anyone know if the 12V constant wire is fed through a fuse or relay in the fuse box? I'm not all sure where that red wire comes from and what else it might power, however it appears that 12V battery wire is used by the fog light relay. This is for a 1989 MJ. I am possibly going to tap that wire for the DRL relay constant power.

Thanks for the suggestion, I just bought a similar one from Amazon, I'm going to see if / how well it works on my "new" lifted Comanche.