Hey all,

Xj 1996, 4.0 Auto. UK car.

Hadn't driven her for a couple of weeks, jumped in and she wouldn't pull off. So I put her into 1-2 gear, then changed the gears manually between 1, 3 and drive.

It had happened once before, I unscrewed the grounding cable on the side of the engine near the dip stick. Then she worked again. This time I've tried the same thing with no result. I put the earth cable on a voltage meter to check if the bolts earthing, which it is.

I'm not really a mechanic, more a guesser, any one got any ideas of what to try next before taking things apart?

Cheers

 

Go to www.cruiser54.com and complete Tip 10.

 

Not sure if because mines a UK spec, so everything's on the other side. But I just can't find this fuse, or even be sure on the tcu. See pictures.

 

It's got the purple label on it in the 2nd pic.

To check fuses, just pull them out one by one and check to see if any are blown.

 

You don't think there is any inline fuses like in the picture on the link you sent?

 

Do you have a check-engine light on? Any P7xx codes set? Fluid level looks good?

A 1996 won't have that inline fuse. The box in the first picture with the wide connector and purple sticker is your TCU. The good news is that the transmission is likely fine mechanically since you can manually shift. The two usual causes for trying to start in 4th are no power to the TCU or a bad #1 solenoid. It's very unlikely that the trans computer is bad. If you have a multimeter, I would start by disconnecting the TCU connector and doing some troubleshooting. Verify it's getting power on pins D14 and D16. Measure pins C14,C15,and C16 for the solenoids in the transmission which should have 11-16 ohms of resistance to ground. D3 and D7 should have a low resistance to ground (they connect back to the stud on the engine you mentioned before).

Here's some info on testing the AW4
https://jeep-manual.ru/index.php?page=ATD-AW4

 

Check Fuse 21 in the underhood Power Distribution Center (PDC)



1996 PDC Fuses
=====================
F1 125a Between Battery and Generator terminals
F2 20a Brake Lights/Flashers
F3 40a Starter Relay
F4 40a Junction Block (interior fuses)
F5 40a ABS
F6 30A PCM, TCM
F7 None
F8 60A Starter Relay, Ignition Switch
F9 None
F10 30A ??
F11 None
F12 None
F13 40a DRL
F14 30a ABS Main Relay
F15 30a Radiator Fan Relay
F17 15a Park Lamp Relay
F18 15a ASD Coil
F19 20a Junction Block (interior fuses), Underhood Light
F20 30a ASD (powers Coil, PCM, O2 Heaters)
F21 10A TCM, TCC Solenoid

 

In your first picture, there is some blue/green corrosion on that one connector. While I'm not quite sure what that connector is, it might just be part of or all of your problem. It usually means a water leak is near.

 

Thanks for the advice, but ive given up. Im not a mechanic, and while testing something with a voltmeter doesn't require me to be one, I've got to many other cars to continously spend time on this one. So I'm going to sell her or scrap her for parts.

 

I dont want to seem hasty here, but testing the fuse, and connector at the TCU could be easily done in less than 30mins

If the TCU has actually failed, it can be replaced with a used one for about $50 and once again, only a few minutes

both of those 2 options sound quicker, easier and more economically prudent than scrapping the vehicle

 

I'd agree, but while she's a lovely truck and starts first time every time,... I don't have the time.

I checked every fuse in the engine bay, they're all fine. Started checking the TCU but without knowing which pins to check, I'd have to check all 32 pins. I know you mention which to check but there is no diagram i could find. Also I'm not a small man so getting into the foot well is a nightmare to be able to see what I'm doing.

Here's the old girl

 

Just clean the TCU and its connector with contact cleaner at this point.

 

My TCU failed in my 89. So I drove it with it unplugged for a while and shifter manually. It will not hurt nothing.

Finally went to a junk yard and found two TCU's. I got both for basically nothing. Put one in my Jeep and it started back shifting. Put the other one in my dash in case this one ever goes out.