acidK1

acidK1

Member
Hi all,
As most of you probably won't remember I'm having trouble with my Jatco 5 speed 2002. I have replaced the reverse drum and clutch packs inside this, 2-4 duty and timing solenoids and the TCC solenoid. About 12 litres of fresh fluid put through doing these jobs.

Problem I have is when warm, I get no 5th. When cold it works fine, eventually when I slow down it drops to 4th then won't go back to 5th. All other gears work perfect, fluid is the right level so I'm at a bit of a loss.
I have just looked at the high gear clutch pack in the old reverse drum and I see 1 of the metal spacers that sits between the friction plates, is thinner then the others, can't see it making this the issue if I put the new one in the wrong place :/ if anyone has one on the shelf could I know where the thinner plate should sit?

Any other suggestions very welcome....please 🥺

Cheers :)
 
I'm sure you're on it given your obvious knowledge and your comment about the fluid level, but I would say check, check and check again the fluid level, engine warm, running, cycle though gears etc. Next would be the selector components I guess.
 
Check all the solenoid resistances & the wiring to the ECU ?

Also are you doing the correct fluid fill procedure ?

Lots of info in this thread, although the OP never came back with the final result.
 
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I checked all resistances and they showed ok however the 2-4 solenoid was still bad. Correct fluid procedure done each time :)

I have pscan, no faults on the car, and 1 on the transmission which is 'p1605 keep alive memory test fail'.

My only option at the moment is chuck a new old auto box in ATM.

Cheers :)
 
What do you mean "2-4 solenoid still bad" ? Also what fuild type are you using ?
 
Having downloaded the Jatco manuals and updates, has anyone got a diagram or list that shows which components operate in which gears ??

I have a TD4 auto here (wife's) that sometimes bangs into 3rd and sometimes doesn't. Most noticeable with gear change when not under much power.

Not inclined to strip the box yet as it works fine, but apart from solenoids, which clutches and drums are in use for 3rd?? Haven't changed solenoid yet but it tests out OK.

Thanks.
 
I tested the resistances and all came back fine, but still had the harsh gear change, changed the 2-4 duty and timing solenoids sorted this. Apparently resistance only says if the coil is ok and not if the solenoid is actually operating / stuck etc. I used carlube atf-u which was recommended by several people on here I believe. I just find it odd to only be happening in 5th, guaranteed, when it's warm. Occasionally if Im cruising and I back off the accelerator a touch, the revs drop to where I would think they would be in 5th, but as soon as I push the revs fly back up to 4th. Not sure if I mentioned but if I put it in 'sport' I can nudge the stick forward and the Speedo display will show 5th, even though it's not in that gear.

:)
 
Fluid needs to be N402 equivalent. Not sure about ATF-U, but tomorrow I will check what we used after doing my Son's reverse clutch band. He works in the parts trade, and looked it up on databases us mortals cannot access !!
 
So after extensive trials to identify exactly when the 'hard change' occurred, I conclude the following:
Only when changing up.
Only on 2 to 3 or 3 to 4 gear changes.
Worse when cold.
Not always present, sort of about 1 in 10 changes.
Worse when not under power - so level ground and little power on.

Anyone know what bits do the above gear changes?
2-4 duty tests out ok, but, as above may be sticking.

Thanks
 
andyfreelandy said:
So after extensive trials to identify exactly when the 'hard change' occurred, I conclude the following:
Only when changing up.
Only on 2 to 3 or 3 to 4 gear changes.
Worse when cold.
Not always present, sort of about 1 in 10 changes.
Worse when not under power - so level ground and little power on.

Anyone know what bits do the above gear changes?
2-4 duty tests out ok, but, as above may be sticking.

Thanks
Click to expand...
Mine was pretty consistent hard changing, the solenoid tested ok but put new one in and it sorted it. Have you tried changing the oil?
 
Thanks. What gears were hard or was it all??

Have done 2 fluid changes with no change. It did have a cracked reverse piston which I replaced. Maybe burnt dust as it slipped for a while with the cracked piston.
 
Andy, did you grab all the Jatco files on my google drive ? One of those docs explains which solenoid combinations are used for each gear shift.
 
Just a bit of an off the wall one for you here Andy, but over the last 11 years, my Jatco would exhibit similar symptoms, but they would be when VCU bearings had gone or the VCU was stiff. Three separate occasions over the years. Each time I was convinced it was duff oil or maybe a solenoid. Upon checking the drivetrain and replacing knackered VCU bearings or taking the prop off, the harsh shift dissappeared. Might be worth a look.
 
Hi J.
Was going to look at prop bearings next. VCU test was OK at last service in Spring.

The thump is clearly a gear change but feels like it could be mid car for the noise.

Thanks for the tip. Will drop prop off and see what happens. Also going to check out the engine mount at bottom of engine.

Maybe box is fine but a combo of engine and change speeds is kicking summat worn ??
 
andyfreelandy said:
Hi J.
Was going to look at prop bearings next. VCU test was OK at last service in Spring.

The thump is clearly a gear change but feels like it could be mid car for the noise.

Thanks for the tip. Will drop prop off and see what happens. Also going to check out the engine mount at bottom of engine.

Maybe box is fine but a combo of engine and change speeds is kicking summat worn ??
Click to expand...
Rear diff bushes seem weak on these as well, mine were beyond knackered when I got the truck 👍
 
This thread on the ZT forums has a couple of interesting pointers. https://www.the75andztclub.co.uk/forum/showpost.php?p=1979493&postcount=8

The interesting bit covering 5th gear is:

The fluid temperature sensor can fail in the following ways:
  • Sensor open circuit
  • Short circuit to 12 or 5 volts
  • Short circuit to earth.
The EAT ECU will detect temperature sensor failure when the vehicle speed exceeds 12.5 mph (20 km/h) and the temperature sensor provides a reading of less than -30°C (-22°F). In the event of a fluid temperature sensor signal failure any of the following symptoms may be observed:
  • Upshift to 5th gear inoperative
  • Torque reduction request from the EAT ECU to the ECM inoperative.
 
pwood999 said:
This thread on the ZT forums has a couple of interesting pointers. https://www.the75andztclub.co.uk/forum/showpost.php?p=1979493&postcount=8

The interesting bit covering 5th gear is:

The fluid temperature sensor can fail in the following ways:
  • Sensor open circuit
  • Short circuit to 12 or 5 volts
  • Short circuit to earth.
The EAT ECU will detect temperature sensor failure when the vehicle speed exceeds 12.5 mph (20 km/h) and the temperature sensor provides a reading of less than -30°C (-22°F). In the event of a fluid temperature sensor signal failure any of the following symptoms may be observed:
  • Upshift to 5th gear inoperative
  • Torque reduction request from the EAT ECU to the ECM inoperative.
Click to expand...
That's an interesting one. Pscan has a live data thing so will see what temp mines reading :)


Thank you :)
 
pwood999 said:
This thread on the ZT forums has a couple of interesting pointers. https://www.the75andztclub.co.uk/forum/showpost.php?p=1979493&postcount=8

The interesting bit covering 5th gear is:

The fluid temperature sensor can fail in the following ways:
  • Sensor open circuit
  • Short circuit to 12 or 5 volts
  • Short circuit to earth.
The EAT ECU will detect temperature sensor failure when the vehicle speed exceeds 12.5 mph (20 km/h) and the temperature sensor provides a reading of less than -30°C (-22°F). In the event of a fluid temperature sensor signal failure any of the following symptoms may be observed:
  • Upshift to 5th gear inoperative
  • Torque reduction request from the EAT ECU to the ECM inoperative.
Click to expand...
I was so hopeful it would be this simple, however pscan shows gearbox oil temperature where I would think would be right. 6C this morning, went for a drive and couple hours after (due to rain) plugged in again and it was showing 22C so looks like that's ok. Appreciate your help though :)
 
Sounds too low. The filling & fluid level check says the box should be 35-40degC. That's after the cold refill & idling after running the box through the various gear selections.

This is from the Jatco Decsription Doc. You can check the sensor resistance values.

1731929846959.png
 
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