V8 D2 Auto stuck in first until 2800rpm, then limp mode.

[jskerm]

Hi all, as the title suggests I am having a very frustrating problem with my Disco. I have just put the whole powertrain back in as a single unit after rebuilding the motor, the transfer case and two diffs. The only thing I didn't do was the auto box and it's the only thing playing up!

What happen is as you accelerate the car is locked in 1st. It stays in first until you hit 2800rpm and then bangs into limp mode, goes to third or 4th and M and S flashing. If you have the car in low range it doesnt change gears just stays in 1st but flashes M and S. In high range before it goes into limp mode (below 2800rpm) if you are in 1 the TC is locked, any other position and the vehicle overruns down a gradient.

There is also a slight rattling noise around that 2800 rpm mark but could be unrelated.

I have checked the following.
-EAT ECU does not send a signal to change gears until it hits limp mode, thats why I think its an electrical problem.

-When you manually earth the pin for solenoid 1 or 2 it goes straight to limp mode so can't trick into changing to second.

-TPS is sending correct signal to ECM

-Vehicle speed is registering on speedo so assume that's all working.

-Engine runs ok so assume Crank position sensor is working.

-Brand new fully charged 1000CCA battery installed

-NO MIL light on dash, only M and S

-Rear most sensor on Transfer case for High Low shaft was not working when I put it back in, but this sensor is also not attached to the vehicle loom (why are there two?). Both difflock sensors working.

-XYZ switch tested and working.(checked at EAT ECU so wiring ok too.

-No amount of stubbies and head scratching has solved problem....

I know I need to hook in a reader which I have ordered and am waiting for from UK (Lynx), but I was hoping someone out there has had similar symptoms. I found one users post describing the same systems back in 2010, but it was never resolved or not written about if it was.

I am currently thinking it might be a CAN fault, it is like the EAT ECU is not getting the message about road speed, throttle position from the engine ECU, is there a way of testing this circuit?

Surely I am not unlucky enough that the trans or TC has :censored: itself whilst sitting on the workshop floor, was working when I took it out....??

Any advise greatly appreciated. I am sick of studying the Workshop manual trying to find the magic answer!


John

[Roverlord off road spares]

Are you sure you seated the TC correctly into the bellhousing. I posted something a while back that you can not have it seated correctly even when it clunks. ashcrofts gave a TC height when correctly installed according to the Serial number. It is easy to brake the oil pump if not correctly seated. Not oil pumping correctly then "no drivee good"

[jskerm]

I never checked the height when I put it in but did turn the torque convertor housing and internals so they engaged with the spline and the cutout for the pump. I'm not saying I have definitely got it right but it seems strange to me that it drives at all if I haven't. Also the fact that the eat ecu isn't sending the signal to change.. You would think that if it was an oil pressure problem it wouldn't drive at all, and if it was driving you would see a signal to change gears from the eat ecu..
Starting to dread the fact i might have to haul the whole lot out again to check it out...

[sierrafery]

IMO be patient untill the tester arrives and it will point you in the right direction, otherwise it's a guessing game, you can't check the CAN messages with multimeter only the bus continuity if you want... did you check the ECU res plug for oil ingress? cos that could disturb the CAN, also the other loom to solenoid pack and output shaft sensor used to be chaffed on top of the gearbox, unless the sensor is not fubar'd

[Roverlord off road spares]

I never checked the height when I put it in but did turn the torque convertor housing and internals so they engaged with the spline and the cutout for the pump. I'm not saying I have definitely got it right but it seems strange to me that it drives at all if I haven't. Also the fact that the eat ecu isn't sending the signal to change.. You would think that if it was an oil pressure problem it wouldn't drive at all, and if it was driving you would see a signal to change gears from the eat ecu..
Starting to dread the fact i might have to haul the whole lot out again to check it out... Yeah it probably wouldn't drive. . But re the fitting of thre TC Mine clunked in to engage, but the height was wrong, so i turned mine and it clunked down a further 2 times to get it seated correctly.

[jskerm]

Right. Got the Lynx delivered the other day (which if anyone is interested is a fantastic product) and downloaded a plethora of codes from the EAT ECU. I think most of them were from having the ignition on with everything unplugged. I cleared the lot and went for a spin. Usual thing happened at 2800 and went into limp mode.
Fault recorded was a stall speed monitoring fault P0722. I went into the live data and found that the output speed of the auto was not registering even though I had checked it earlier with a multimeter. Obviously not well enough.
After checking all the wiring thoroughly I couldn't fault any of it so removed the sump from the auto to inspect the sensor itself. Pulled it out and with it still plugged in I held it up to a makeshift toothed wheel on a drill and had a look at the live data, and, got a reading.
So, after a bit of head scratching I had a look in the sensor hole and it looked like the toothed wheel on the output shaft was not actually in line with the sensor. Bugger.
So whatever holds the speed ring on the output shaft has come loose, allowing the ring to move backwards enough that the sensor won't read it.
Obviously something has come adrift inside the transmission allowing this to happen but I am wondering if anyone has come across this before? I cant see much in there but I suspect maybe the whole output shaft is moving.... Looks like I might be rebuilding a tranny afterall. At least I will pretty much have a brand new vehicle after this!
Does anyone out there know where I can access a parts diagram or workshop manual for a 4HP22EH? Just wondering what I have done wrong to cause this when assembling.....

[gazk]

I had a similar issue occur on my TD5 auto a few years ago when a rebuilt transmission was installed by a L/R mechanic - the transmission would not shift out of first - the output sensor was not aligned with the toothed wheel due to the bolt that holds the output shaft on not being tightened properly. (that shaft holds the output speed sensor"toothed wheel" in place)

[jskerm]

Where was that bolt gazk? I gather its internal, but is it something that I could have damaged whilst installing?

[gazk]

It is the bolt in the end of the output (extension) shaft that goes into the transfer case - you will need to remove the transfer case to tighten it.

You can see the head of the bolt in the end of the output shaft on page 44-41 (figure M44-1058) of the workshop manual.

[Collins]

I have a copy of a LR Document relating to RR auto transmission, and particularly from Pge 22 on to the Bosch 4HP22/24EH transmission, but I am not able to copy it for transmission.
If anyone can advise me on how to copy it I could upload it to the forum.
Please advise.
I am seeking advice from my IT Programmer son & will forward ASAP
Unfortunately unable to upload due to file corruption

[jskerm]

88036
This one?
Buggered if I noticed it when it was out on the ground!
I will pop off the pto cover tomorrow and hopefully I can access it through the transfer input gear, if not i should be able to take out the transfer input shaft and get to it without removing the transfer case...
Gary, you're a legend if this works!

[gazk]

That's the one. I don't think you will be able to tighten it without removing the transfer case.

[jskerm]

Finally got five minutes to get back to this. Pulled the pto cover off the back of the transfer and removed input gear. Guess what, head broken off the bolt. Must have knocked it when installing. Anyway pulled the broken bolt out, put a replacement one in and bobs your uncle, I have four gears again. Thank you very much gazk for your advice.

[worane]

It is this sort of wonderful talent and the willingness to share it that makes this forum the great place it is.
Well done Gary. Happy New Year to you all.
Regards Nick.

[Jazzman]

It is this sort of wonderful talent and the willingness to share it that makes this forum the great place it is.
Well done Gary. Happy New Year to you all.
Regards Nick.



I concur!