G switch question-Is Chrysler screwing us?

[falcon556]

Or acceleration switch. Under the rear seat in XJs with ABS.
I believe it is an accelerometer. According to the manual it "provides an additional vehicle deceleration reference during 4WD operation."
My question is, how does the 4X4 information gets to the ABS controller?
I checked the wiring diagrams repeatedly, I don't see anything.
The wiring diagrams of the transmission controll and ABS controller are not drawn in solid lines in the FSM, which means that the shown unit is not complete.
I have not been able to find the missing wiring info.
Is Chrysler hiding them from us?

[ChicksDigWagons]

I'm guessing its a line of bull.

[falcon556]

I'm guessing its a line of bull.

Sorry you see it that way.
Just follow me for a moment, the only part that knows that the XJ is in 4x4 is the transfer case switch. The only place in the wiring manuals that you'll find the transfer case switch is under "indication" 8W-40.
There it shows the switches of both 231 and 242 TCs in solid lines which means that the units are shown complete. The wires from those switches provide a ground for the 4x4 indicator lights. No splices, nothing. In other words, nothing in the XJ besides the 4x4 lights gets the information that the XJ is in 4x4.
That can't be right when the same FSM states that the ABS controller does something else when in 4x4. To make things more interesting the ABS controller is not drawn using solid lines in any wiring diagram, which means that all the wires going to it are not shown.
Pardon me for putting two and two together and you can verify everything I say. AFAIK it is illegal for auto companies to hide information needed for the safe operation of the vehicle. I seem to remember that they lost a class action suit on this issue.
This is not BS, I need to know these details, I have made modifications based on the FSM wiring manual that may compromise the safety of my XJ.
I'll tell you what I think. I think that when the TC switch is in 4x4, one or more of the wires goes through the trasmission control module to the transmission controller. From there I think they have one of those "missing" wires going to the ABS controller.
I'd appreciate it if somebody with other than FSM checks it out.
TIA

[jneary]

what year is the jeep?

[falcon556]

I am mainly interested in the 99 and 96, I think it applies to many years.
I checked the FSM of 96, 97, 99,00.

[jneary]

i believe it uses it for reference when you descend down hills forward or backward like when you are 4 wheeling. inside the sensor is two contacts, one can roll out in a foward direction to sense foward motion and one can roll out in out while braking hard in reverse to sense a hard braking while backing up. its hard to explain but i hope you understand. this sensor rarely goes bad.

[falcon556]

i believe it uses it for reference when you descend down hills forward or backward like when you are 4 wheeling. inside the sensor is two contacts, one can roll out in a foward direction to sense foward motion and one can roll out in out while braking hard in reverse to sense a hard braking while backing up. its hard to explain but i hope you understand. this sensor rarely goes bad.

"during 4WD operation", not during operation over rough terrain.
It implies 4WD sensing.
There are several reasons that I think there is more to it.
As far back as my '87 XJ the wiring diagram shows the wire for the light going
through the trasmission. I have that available right now, I can email it on request.
Another time in the FSM of a '97 to '00, sorry I can't find this refference any more, it stated that the green light was controlled by the transmission controller. That coupled with the fact that neither the transmission controller or the ABS controller are shown completely, makes me believe that we are missing information.
One way to know for sure would be if someone has the TC and transmission harness of a late XJ with a 242 TC. Tracing the wires would prove or disprove my suspicion.

[jneary]

87 and 99 are 2 way different jeeps. the g-switch is directly wired to the abs controller on the 99. it aids in abs braking under circumstances as i described

[jneary]

it has nothing to do with the transfer case

[falcon556]

Thanks, the way I read it I thought it implied a connection between the ABS and the transfer case, I thought it was happenning through the transmission.
I'll keep looking.

Just found this in the '96 FSM page 8w-40-3
" On vehicles equipped with the 4.OL engine and an
automatic transmission, circuit G107 connects to the
solenoid assembly in the transmission. Circuit G106
from the solenoid assembly provides ground during
4WD Full Time operation."
That means that the transmission knows when in 4X4.

[jneary]

i didnt see it on a wiring diacram, but the FSM states it is wired to the ABS. hope that helps

[falcon556]

i didnt see it on a wiring diacram, but the FSM states it is wired to the ABS. hope that helps

Yes it is, one wire for testing and two for sensing.
Thanks.

[ChicksDigWagons]

Woah Woah Cowboy. This isn't a chrysler conspiracy to get you killed!

What I meant was it was probably an ultra simplified statement. ABS systems are incredibly complicated especially for an off-road destined vehicle. Its hard to predict the conditions a vehicle will be in and adapt accordingly when you take it outside of the realm of pavement. Sounds like its just some feedback for the ABS to adjust for changes in yaw or pitch? Nothing to worry about.

[falcon556]

Woah Woah Cowboy. This isn't a chrysler conspiracy to get you killed!

What I meant was it was probably an ultra simplified statement. ABS systems are incredibly complicated especially for an off-road destined vehicle. Its hard to predict the conditions a vehicle will be in and adapt accordingly when you take it outside of the realm of pavement. Sounds like its just some feedback for the ABS to adjust for changes in yaw or pitch? Nothing to worry about.

Thanks, I keep thinking I'm missing something.
I'm taking it too seriously, I just hate loose ends.
Thanks everybody.