Ive only been able to find G102 (DipStick ground) hooked up to the DataLink (ODB2) and the anti-lock brake system. I have a 8.25 rear axle and I believe these didn't come with ABS.
I have found wires Z1 BK and Z12 BK/TN (same as G102 wires) in other parts of the electrical system but they aren't routed directly to G102.

Hoping ripping apart my harness will help me find anything else.

 

Post #20 in this thread:

https://www.cherokeeforum.com/f30/en...130071/index2/

Pic attached re G102...

 

Roler,

Ive cleaned G106 and i get good voltage and continuity out of them. Battery G100, 2 on the block G101, and the on off the back of the head all have 12V and continuity. G102 is the only one in the engine bay that doesn't have continuity to the negative terminal and a pulsing up and down voltage from .01mv to .180mv. Two days ago it was doing this fast but last night it took about 10 seconds to go up and then blip back to .01mv.
Ive traced on end of G102 to the ODB2 port. Wiring diagrams say it also goes to the ABS system but I dont have that. Didn't have enough time to see if it went anywhere else.

Early on in my no start investigation, I did find a PCM pin that would make my test light go on and off. The plug was unplugged so it wasn't getting anything out of the PCM. Ill have to dig that up later tonight to see if its connected to all of this mess.

 

Woohoo!! Found a worn spot on a ground G102 ground wire! My P0122 and P1694 codes went away!

BUT it still won’t start. Now I’m thinking CPS. It was pointed out to me that my flex plate sensor windows are a 1/4 inch further away from the ring gear than stock. I’ll test it again tomorrow and if it checks out, I’ll shim it out a little and try again.

 

Still haven't figured this one out. Tried a new CPS sensor, shimmed the CPS. Got a new CAM position sensor and that didn't work. I basically have no power to Fuse 21 and 18. I have continuity between ASD and PCM for both the control and output circuits. Control = PCM C3 pin 3 K51 18DB/YL ASD D4(Start circuit) Output = PCM C3 pin 12 F142 18DG/WT to Fuse 21 to ASD D8 (Powers Fuse 18 which powers coil and injectors). I dont have any voltage on the output side. Am I supposed to?

Think this could be PCM related? Whats a good test to verify if its ok? Currently researching this process.

 

Lets step back and be systematic

Here are some things I would try

* Verify you have power at fuse 8

* verify you have power at the female terminal of the ASD relay socket in the PDC

* disconnect fuse 18, and fuse 21, and see if power shows up at the other one, with and without one fuse
(Its like having 2 power circuits in your house, if one has earth leakage, you can pull the fuse, and at least you have power on the other circuit, gives you a hint to where the problem is too)

* using or building a relay socket and jumpers, mount your ASD remotely

* disconnect the PCM wire and ground out the ASD terminal that formerly went to the PCM . See if this gives power to fuse 18 and 21. It should

Most likely is a poor wire or connector

I believe the ASD relay will shut down a short while after energising if conditions are not met, so be ready to check for power right away

As far as I can tell, disconnecting the PCM from the ASD and earthing it manually should energise it, provided it has 12V at the power terminal.
The PCM is cut "out of the picture, so cannot shut of the path to ground

If those tests all work, further investigation can be done

Apologies if you have done some or all of these tests before.

Electronic fault finding must be systematic

 

AWG,

Fuse 8 in the PDC has power
Fuse 8, 9, 10, 11, 27 in my junction box all have power when I turn my ignition on. Fuse 11 powers PCM, TCM, ASD, Fuel Pump Relay. Fuel pump kicks on for a few seconds when I turn my key to run. I also get 45-49 PSI of fuel at the rail.
ASD has Battery power at D2 (power comes from Fuse 8 in PDC) and Ignition power at D4.(power comes from Fuse 11 in Junction Box) FSM wiring diagram 8W-30-2 shows both circuits.
Both 21 and 18 have no power in any plugged in or out combination. They are both connected to ASD Terminal D8
Ive jumped ASD from D4 to D8 and Fuse 21 and 18 power on but the engine still wont start.

* disconnect the PCM wire and ground out the ASD terminal that formerly went to the PCM . See if this gives power to fuse 18 and 21. It should
Most likely is a poor wire or connector : Im not following. PCM C3 has both ASD control Pin 3 and ASD Output Pin 12. Control goes to ASD D6 and Output goes through Fuse 12 to ASD D8. From these descriptions, can you tell me which one needs to be grounded? Am I back pinning the wire or do I unplug C3 completely? Does the ignition need to be on? I am assuming ASD relay is still plugged in. correct? I know both the output and control wires have continuity to the PCM from ASD and fuse 21. Just not sure what the voltages specs should be for each wire with ignition on.

With my ignition on, I have unplugged the ASD Relay, hooked up a test light to the Negative Terminal and touched Fuse 21. When I put the Relay back in, I hear it click and the test light will blip on for a quick sec. This is telling me the relay is closing, realizes things aren't met and then opens back up. This is making me wonder if Fuse 21 and 18 are supposed to be off until the engine cranks.

I ran down the DG/OR wire from fuse 18 to the coil rail and I have continuity. Haven't tested for continuity between all the ignition drivers and the PCM but I know where they are.
I also messed around with the NSS last night just to be sure and its still looking good.

Something I noticed in one of the photos I took of my new flex plate after I had it on the jeep for a few start attempts was a line kind of rubbed in the sensor band. The band with the 12 windows. Im guessing my CPS was rubbing on it. Can this be an issue? I unbolted my CPS a little to see if it would move further back but there was no wiggle room. Ive read that the CPS on older jeeps came with a shim. Looks like on 2000 XJs, this location is predetermined. Remember I have tried 2 jeep CPS and one from oreilly's.

 

The PCM allows the ASD to operate by supplying ground, if it doesnt for any reason, there can be now power downstream of the ASD

I am suggesting disconnect the wire from PCM to ASD that provides ground, and ground the ASD to see if it operates

The downstream feeds to 18 & 21 may have a short or open wire, hence why you should be systematic, testing every wire, and remotely mounting the ASD as I suggested

If you dont want to go that way, you could obtain a used PCM and see if that fixes it

If the fuel pump operates, that is a positive clue

I have not studied the whole thread, but is is absolutely known that flexplates are different for different years, you mention you changed yours, you may need to compare it with the old one to see if anything is different, several people have had that issue

 

awg,

I follow you now. I miss read your last message. I can rig the ASD up remotely and ground it out. Looks like its the DB/YL wire from C3 pin 3. ASD Relay Control. This is a straight shot to the relay and works with the ignition power to close the relay to make fuse 21 and 18 work. Ill try that tonight.

My new flex plate is pretty spot on. I have a bunch of photos of them side by side. All 12 signal windows are in the right location as are the 6 mounting holes and 4 torque converter holes. On 2000 XJs, the flex plate can only go on 1 way. The only difference is the balancing holes in the face (every flex plate has them in different locations) and my 12 signal windows are about 1/8th of an inch further away from the ring gear than stock. I know it works because Ive been able to fire up my jeep twice during all of this mess with my original CPS. CPS gets 12v from battery, 5v reference, and goes between 0 and 5 v when I rotate the flexplate which means its reading properly.