AW4 Wierdness

[BigIrish]

All right. I already searched and nothing seems close to this. My AW4 in my 95 XJ will not shift by itself. It acts like it has a manual valve body installed. I put the shifter in drive and the trans will be in drive. As long as I shift manually it shifts fine but it will not do it on its own and will be in whatever gear I put it in. It is also not throwing any trouble codes and no fuses are blown.

Any body have any ideas or wanna trade transmissions?

[BrettM]

check and see if you're getting battery power (12-14v) to terminal D16 on the wire harness.

[BigIrish]

Is D16 marked? If not on which of the three I have running to the trans and what pin.


ETA: Nevermind. You are speaking of the connector on the TCU.

[BigIrish]

Anybody have a diagram of the pin layout on the TCU connector. I found it yesterday, but can't seem to find it today.

Anybody else think the search function here sucks?

[XJAnthony]

in my 91 i had the computer under the dash on the pass. side unhooked and it kinda did the same thing, hope it helps

[BigIrish]

Ok, so I found D16, I think. It was the last one (yellow) two away from a larger guage (red) wire that is always hot. I have no power going to the yellow wire with or without ignition on. So without going any further I attempted to locate an inline fuse and resistor pack which should have been right next to the TCU on the harness. I followed the harness all the way back to the firewall (behind the heater box) and could not locate the fuse/resistor. I have read that this resistor pack shorts out and blows the fuse and commonly causes this problem but I can't locate it. Any ideas on an alternate location. My jeep is a 95 4.0.

[Saudade]

In the '93 FSM, the wiring diagram shows the yellow wire on D16 connected to Fuse #3 in the power dist center next to the coolant overflow bottle.

The other "end" of the fuse is a dark blue wire going to the ign switch.

[BigIrish]

In the '93 FSM, the wiring diagram shows the yellow wire on D16 connected to Fuse #3 in the power dist center next to the coolant overflow bottle.

The other "end" of the fuse is a dark blue wire going to the ign switch.

You are speaking of of the 10 amp "mini" in the rear/passenger side of the power distribution center? Already checked this fuse.

If I can not locate the resistor pack and fuse is it possible I do not have one?

[Saudade]

There was nothing in the wiring diagram that suggested anything inline. It went straight from the TCU to the PDC. You said "check", did you do this visually, or with an ohm meter?

I can check the diagram better later to see where on the ign switch it goes. I'd post the diagram for you but it's a poor copy to begin with and a at decent resolution to upload, it would likely be unreadable.

If you google XJ FSM, you'll likely find a source the the same one I'm using.

[SLOPAR]

You are speaking of of the 10 amp "mini" in the rear/passenger side of the power distribution center? Already checked this fuse.

If I can not locate the resistor pack and fuse is it possible I do not have one?
Whoa, hold up, I know where the fuse center is by the coolant bottle but is there one in the rear too? I ask because I am having the same trouble you are so I am eagerly awaiting your findings................:repair:

[BigIrish]

No, I was speaking in relative terms about the fuses location inside the box.

I'm thinking of just running a new ign sourced wire to the one on the TCU and seeing if it fireballs.:flame:

[SLOPAR]

No, I was speaking in relative terms about the fuses location inside the box.

I'm thinking of just running a new ign sourced wire to the one on the TCU and seeing if it fireballs.:flame:
10-4, if it does I have a replacement TCU for ya' I'd let go real cheap.

[corbinafly]

You are speaking of of the 10 amp "mini" in the rear/passenger side of the power distribution center? Already checked this fuse.

If I can not locate the resistor pack and fuse is it possible I do not have one?
My '95 FSM doesn't show any other fuse between D16 and fuse 12 in the PDC (10 A). Make sure the fuse is good with a meter. You should have power going to D16 with the ignition on.

Kyung

[lawsoncl]

My '95 FSM doesn't show any other fuse between D16 and fuse 12 in the PDC (10 A). Make sure the fuse is good with a meter. You should have power going to D16 with the ignition on.

Kyung

Ditto. Check that you have power at the fuse too. The power to that fuse comes from the ign switch. There is no inline fuse or resistor to the TCU like the older Renix's had. You also don't have the power/comfort switch, but the FSM shows a connector C114 somewhere for hooking one up. Don't know if it'll do anything if you do connect something to that connector though.

Connecting D16 to a constant power would be a good check, but don't leave it that way or you'll drain your battery since it'll be powering one of the solenoids the entire time.

[BigIrish]

I just used the eyeball test on the fuse. I did comfirm that that fuse is getting power with the ign on. I had the meter on the fuse but did not see if it was blown with the meter. Still have not given it the "hotwire" test, been busy.

[BigIrish]

Ok, I checked the fuse and I am getting .5 ohms - Fuse good. I took the wiring harness apart and followed the yellow wire the entire length and could not find any breaks. I cut the yellow wire 4 inches from the fuse in the PDC and installed a new length of wire and wired it directly to D16 on the TCU connector.

Figured this would be the fix (at least temporarily). Got in, fired it up, and put the shifter in "D". Went to pull out and it still starts in 4th gear.

Looks like new TCU time. Any other ideas.

[corbinafly]

Ok, I checked the fuse and I am getting .5 ohms - Fuse good. I took the wiring harness apart and followed the yellow wire the entire length and could not find any breaks. I cut the yellow wire 4 inches from the fuse in the PDC and installed a new length of wire and wired it directly to D16 on the TCU connector.

Figured this would be the fix (at least temporarily). Got in, fired it up, and put the shifter in "D". Went to pull out and it still starts in 4th gear.

Looks like new TCU time. Any other ideas.
You did confirm that you had ~12v at D16 on the tcu after doing the wiring right? Just checking...

Kyung

[BigIrish]

Si, Senor. I ran a wire directly from a known good ignition power source and confimed with a voltmeter that I had 12VDC at D16 on the TCU connecter.

[BrettM]

did you check the ground?

[lawsoncl]

Here's a list of things to check on the connector while you've got the ignition on (engine running shouldn't matter).

+12 volts on D14, red wire fed from fuse 2 in the PDC
+12 volts on D16. yellow wire fed from fuse 12 in the PDC.You've checked that already.
Good ground on D7, black wire with tan stripe

C14, 15, and 16 are the solenoid outputs. Sitting still, you should have power to solenoid 1 only (C16 on the TCU, dark blue with white stripe). If you pull the connector you should have around 11-15 ohms between the solenoid pins in the wiring harness and ground. If not, you've got a bad solenoid or wiring issue.

If everything looks good, but you're still not seeing power coming from the solenoid you might have a bad TCU. I have a 93 XJ TCU, part number 56026769 I can ship you for $20.

[BigIrish]

C14-16 all read 12-14 ohms. D7 reads 2.3 ohms. All measurements were taken using the ground wire from the radio harness as a known good ground.

[BigIrish]

My TCU P/N is 56026769 so It appears you have what I need. PM sent.

[lawsoncl]

C14-16 all read 12-14 ohms. D7 reads 2.3 ohms. All measurements were taken using the ground wire from the radio harness as a known good ground.

The D7 ground seems a bit off. I wonder if tying it to a good chassis ground would help?