rgrosiak

Hi guys,
I'm from Poland but decided to post here as I can't find answer anywhere.
I'm installing AW4 in my ZJ and doing the wiring I noticed the problem with Pin C8 on TCU. According to below photo this Pin must receive the signal from neutral/park switch that tranmission is in D position.




This is clear but I noticed that my switch actually does not have the Pin that could send this signal. Except Park and Neutral it has R,3 and 1-2 positions pins but not for D position, exactly like on the pic below I found in the AW4 manual and I guess all switches are the same for all XJs up to 96'





So, how actually this wiring schould be done ? On the wiring diagram it is clearly showed "D" but I don't have this Pin in the switch.According to the wiring diagram and Pin's names this sinal wiil be sent to Pin8 via pin Gfrom the switch when transmission will be in position "3", is that correct ?? I thought D means D, it is really not clear for me.

Thx in advance for your help

CCKen

What year XJ are you working on?

rgrosiak

AW4 and TCU are 93', as I wrote I'm installing it in ZJ but anyway it doesn't matter so we just can treat it as XJ 93'

CCKen

You should be concerned about pin 9 on the TCM, not pin 8.



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rgrosiak

You're right, my mistake, of course it's pin9. But anyway my question is still valid, this Pin2 called Gear Drive in your posst in which position of lever is turned on ? in D or 3 ? if we assume all Park/Neutral sensors are the same up to 96' Xjs really I checked it and there is no signal on D position, also AW4 manual tells the same, below pic is from AW4 manual, so looking at the wiring diagram I showed in the first post looks like

1. I wrongly understand "D" in this diagram
2. There is a mistke in wiring diagram and it should be "3" instead of "D"
3. There are dfferent park/neutral sensors ??

CCKen

You may be confusing that Fig. 2 chart with the actual function of the transmission. That chart gives the pin combinations for testing continuity of the Park/Neutral Position Switch, not the functions of the transmission. There should be continuity between each of those switch positions shown when the gear shifter is placed in those positions. When Drive (D) is selected there should be no continuity.

The Park/Neutral Position Switch tells the TCU what gear selector position you have manually selected. When Drive (D) is selected the TCU sees the signal (Voltage) from the PNPS then it activates the solenoids in the transmission based upon transmission speed, and TPS signals, from 1-2, 3, then overdrive.

Here's a few wiring diagrams you can study and a photo of the solenoids and a description of their electronic functions.



.

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rgrosiak

Thank you very much for your answer, however I'm still blind
...When Drive (D) is selected the TCU sees the signal (Voltage) from the PNPS .... can you please describe what PNPS means ?

Again this is confusing, on the diagrams you showed there is again "D"



At the same time you confirmed there is no continuity in the park'neutral switchwhen transmission lever is on D position so what this D means on this diagram and in which position of lever this circuit will be closed ? in position 3 ?

rgrosiak

Ok, I think by PNPS you meant Park Neutral Position Switch however again, we just agreed this switch has no continuity on D position at all on any pins which is shown on the pics above, so this signal (12V) will come to pin9 only in position 3 not 'D" of tranny lever, that's exactly what is confusiing and I don't understand it

CCKen

No, the voltage signal from the PNPS when "D" is selected goes to pin 9 of the TCM, not gear selection 3.


I think you are reading too much in to this.


What are you after anyway?

rgrosiak

CCken, this is exactly my concern. When drive (D) is selected it is not possible to have 12V on Pin9 of TCM because PNPS has no continuity in this position on any pins.

CCKen

How on earth have all the XJ Cherokees with the AW4 transmission been operating all these years with such mystery surrounding what you are talking about.


I suggest you forget about getting 12 volts to pin 9 of the TCU when Drive is selected and carry on.


I'm done.


Good luck.

CCKen

repeat deleted.

rgrosiak

CCken, thank you very much for your help. I just wanted to understand entire curcuit and how it works, you must agree with me that so far it looks like there is a mistake on diagrams and it should be called "3" not "D" because on a drive selection no any signal comes to Pin9, only on selection "3" Pin G has continuity with PinA in a Park/Neutral position sensor hence 12V will then go to Pin9 in TCU.
This is confusing and that's why I decided to make sure it is true on this forum. Once again thank you very much for your help.

CCKen

There is something wrong in the wiring diagrams concerning the Neutral Safety Switch (NSS) Drive (D) switch (from 1990 to 1996 that I can see) vs. the NSS continuity checks chart. Also, the TCU pin out for the 95 shows the Drive (D) input.


Confusing indeed.


Here's a graphic that shows the 1996 NSS continuity checks (No Drive):



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Here's the inside of a 1996 NSS that shows there's no contact for Drive (D):



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Here's the inside of a 1997+ NSS that shows a Drive (D) contact:



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The part number of the NSS changed in 1997 which would add the Drive contact.


Here's a diagram of the 1997 NSS:



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Here's a pinout of the 1997-2001 TCM. Note the NSS inputs.



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And a diagram of the 1994 TCM inputs:

rgrosiak

So looks like having TCU and NSS uo to 96' I should ignore it and TCU receives signal from NSS only on 3 (pin9) and 1-2 position (pin8), no signal on D position, right ?
It could save my live as started to think I'm crazy