cruiser54

On Trans side, yes.

Gearhead-XJ90

Right on well both TPS are good. My spare is still connected to a throttle body, I set the two side by side just a minute ago. Verified they were set per spec, and then slowly rotated the throttle to WOT. They both seemed the same to me.

Earlier today I also checked the resistance on the wires for the trans side of the TPS, and all looked good (0.0 max 0.1)

All of my sensor grounds are good to go.

DFlintstone

The shop/s' that the PO of my White 90 used were clearly idiots. I see it all over. Do you have a rear wiper, does it work, and did you verify the color code's of the wires going to your comfort switch? Pete could that matter?

Two days in a row, poking my (non functioning rear wiper), switch, it up shifted. Today I left that switch on, and it shifted fine. Anecdotal ( Being unreliable or untrustworthy), shot in the dark. In my case some idiot might have just stabbed wires on the wrong prongs.

Gearhead-XJ90

Wow... I had a 300zx years back, and it was the same case there, but with the vacuum hoses for the HVAC (no less than a ****-ton)

Gearhead-XJ90

I'm going to pick up a new TPS tomorrow and try it out. If it does not change anything at least I can take it back.

C3 on the TCU pinout is road speed. Where does this come from? I thought I had the AW4 manual, but I cannot seem to find it.

DFlintstone

I'm well beyond my depth here. I just trust the AW-4 and figure it's the electrics if it's not slipping. Sure. Btw the PO of White had a TPS in there with a different/cobbled connector. I removed what they did and wire nutted it, and was only barely able to push it over into spec, checking on the trans side.

As I mentioned earlier, both of my 90's don't have a TPS ground there through the TCU, trans side, (as should be expected, I gather from Cruiser). Brown shifts fine.

Besides the remote chance of wires getting mixed up there at the "comfort" switch, trying another TPS makes sense to me. The " dangling participle" (to paraphrase). We know the CPS is functioning. We have a mechanical speedo. What's that "speed sensor" doing?

Gearhead-XJ90

That's crazy because my TPS ground through the TCU. I also found out it only passes ground when the TCU is plugged in.

But then again my harness was a '89.

cruiser54

No matter.

Trans side of TPS grounds through the TCU. Blk on switch to Tan/Org on harness terminating at D3.

Road speed comes into TCU at C3 from a Vehicle Speed Sensor.

P/C switch ground at G102 which is the overloaded instrument panel ground described, with a fix, in my Tip 18. Hmmmmm.

Improving the Instrument Panel Ground

The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release ****. The screw will have either a ¼” or 5/16” head on it.

This ground point is responsible for handling the ground circuit for the following items: Dome lamps, Seatbelt and key warning, trans comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things.

The problem is that where the ground point is located does not have a good contact with the chassis where the ground should be. The solution is simple.

Make up a jumper wire with #10 gauge wire about 10” long. On one end, crimp on a ¼” round wire terminal. On the other end, crimp on a 3/8” round wire terminal.

Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other.

Look above the driver’s side plastic kick panel just forward of the top of the hood release ****. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely.

**Special note for Comanche owners: Make your jumper wire 12” long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.**


Revised 11-29-2011


From the factory wiring manual with a Ground Distribution page in it regarding lighting:

There are 2 points on the left inner fender.

There is the engine dipstick tube stud. SUPER IMPORTANT!!

There is the ground above the lower diagonal dash brace to the left of the steering column on the shiny part of the dash.

There is one in behind the trim panel where the spare tire mounts.

The one on the instrument panel grounds a ton of things. Probably too many things as a matter of fact, given it's poor mounting point on the panel with a self tapping screw. I remove the screw that it's held on with, add a wire, using 10 gauge, and terminate it to the stud near the fusebox.

There are also grounds from the engine to chassis, notably the poor one from the back of the head to the firewall but that wouldn't affect your dash lights. Not that the engine to chassis grounding shouldn't be addressed.

Gearhead-XJ90

The local auto parts house should have my TPS in the next hour or so. I will give that a try. Worse case I have a new TPS installed.

cruiser54

I'm still bugged by the G102 ground in both yours and Flintstone's Jeeps.

Gearhead-XJ90

I've got the TPS in hand. After I saw the Tip 18 post above, I decided to do that as well, so I'm driving out to the warehouse in a few minutes to take care of that.

Other than the G102 ground, all of my ground wires have been updated. I saw what a person that you refer people to for upgraded battery wires had to offer, then more-or-less replicated it myself. I did add more ground wires in all the good spots. I used 2ga and 4ga wires, with the 2ga running to the stud on the engine block.

Post edit: This is just an assumption, but if the transmission speed sensor, mounted before the transfer case on my transmission, was bad would it change only the 1-2 shift point and nothing else? I did pull that down and clean the contacts on it after breakfast, but nothing changed. Maybe pull it out and check for steel collecting on magnet? My guess is it would screw up all shift points not just the 1-2.

Gearhead-XJ90

I've got to add this just because.

When I took apart and cleaned my NSS, I finally had reverse lights for the first time since I bought the XJ. My wife pointed it out to me when I backed out to do a test drive. She asked me if I "finally got around to changing the bulbs?"

I think the write-up I read about it was yours as well.

Gearhead-XJ90

Problem solved, I guess. I can't for the life of me get a 15MPH shift out of it, but maybe the TPS was adjusted wrong for a long time.

I did Tip 18 with 8ga wire because I had no 10ga. Then I forgot to test drive before I did the TPS swap. I get a part throttle shift at 20MPH.

Thank you Cruiser for all of your time. Flintstone I hope you solve your problem. I would start with #18. I also soldered the wires for the p/c switch and slapped a Carling cover (had one laying around) to hide the hole removing the switch left.

Off to work on my next problem.

cruiser54

Good old Tip 18....Gauge of wire is less important than just upgrading the ground circuit.

DFlintstone

Firstly lets clarify..both the instrument ground, and the TPS swap happened at the same time, and after that shifting seems OK?