hypersthenos

Hey all. Haven't been on here for awhile as all has been well with my XJ. Idle is just a bit high (to my ear) so I decided to adjust the TPS (thank you CRUISER 54!). Problem is I've got 1.7 ohms of resistance between the negative battery post and terminal B at the TPS sensor. I've already done the obvious negative ground improvements as outlined in CRUISER 54's excellent write up to no avail. I've wiggled the harness all over and cannot get a fluctuation with my meter. Anyone know of some common problem areas of the wiring harness for the sensor grounds so I'm not tearing things completely apart? Let me know. Thanks!

DFlintstone

Didja really get into those crimps? (the grounds have crimp splices under that casing). Soldering has been brought up. Cruiser will be along...but in the meantime some of his stuff is in my sig. You cleaned your IAC?

cruiser54

Here it is:
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 stripe 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 with duct tape over them. 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 with duct tape over them. 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 03-09-12

hypersthenos

Thanks to both of you for the reply. Cruiser 54 this is exactly what I needed. I have not proceeded with cleaning the TB as of yet. Once these ground connections have been corrected I'll proceed. BTW I went reallly crazy with cleaning up each and every electical connection under the hood. I even carefully removed the wire terminals from the plastic receptacles with a fine dental pick, cleaned them and then re-inserted them. I'm sure all of this has helped but I was hesitant to undo the wire looms without better direction. Now I've got what I need. Thanks again!

cruiser54

Good!! The split-loom may crack and disintegrate but it's cheap to buy new stuff. That, and some good electrical tape and you'll be good to go.

Get that throttle body done, too.

hypersthenos

Hey Cruiser 54. Thanks once again. Did the sensor ground repair, TB cleaning and TPS adjusment which went without a hitch. Anyone with one of these Renix era systems should consider that sensor ground repair as mandatory. Not only eliminates the three into one into three conduction path but on my 87 with the C101 connector is bypassed that too. Your instructions were great. I had a roll of friction tape laying around to make up for some of the disentegrated split loom for now. Seems to idle much smoother. I was not having driveability issues prior to this repair but I'm sure I've staved off problems in the future. The only part of your suggested repairs I've not performed is the under dash ground repair. I'll take some Ibuprofen before attempting that one.

cruiser54

I love happy endings. Ibuprofen before and after the under dash work!!