Auto trans fault

Gidday,

Back again with more P38 problems.

I have had an ongoing problem with my automatic trans over the past few years (ever since i owned the beast), but it has been intermittent and not too much of a hassle. Over the last few weeks, the problem has become more apparent and i want it fixed.

When driving along, either under throttle, or cruise control, the trans will chop down a gear and then back up when ever it feels like it. sometimes it may chop up and down frequently, say 10-15 times in a minute. Other times it may chop down and stay in a lower gear (4th gear no lock up i guess) for as long as 5-10 minutes before it changes back up.

At the weekend i took off on a 1000Km round trip (brave under the circumstances) armed with my fault mate msv. The auto played up almost non-stop on the first leg of the trip, so i scanned in stand alone mode and got a fault code for the auto. The fault code was along the lines of " solenoid no power". Being the numpty that i am, i erased the fault, in the hope that the symptom would lessen on the way home.

The return trip was not much better and the auto played up for the best part of the trip. When i did a rescan at home through the laptop i got no fault codes present.

When i have scanned in the past i have not pulled any fault codes, so the fault i did mange to extract may or may not be relevant to the symptom but that is what i am hoping some one can tell me.

I think the fault is electrical as it has been going on for the last 50K and perhaps even longer and i think if it was a mechanical or wear issue then i think it would have failed sooner.

Well here's hoping somebody has had the same or a similar problem and can throw some light on the issue.

Are there any other tests i am able to carry out with the faultmate that may help diagnose the fault?

All ideas greatly appreciated.

Cheers Spadgr

Check the wiring from the ECU to the transmission and the connectors at each end. Then check the transmission solenoid resistances. PM me with an email address and I will sort out the resistance chart for you.
I assume you have checked the oil level using the correct proceedure?

I checked the trans oil, engine running in park after shifting slowly through gears, and if anything it is slightly overfull.
Do i have to pull off the sump to check the solenoid resistances?
I will pm my email for the resistance charts.

Cheers

spadgr said:

I checked the trans oil, engine running in park after shifting slowly through gears, and if anything it is slightly overfull.
Do i have to pull off the sump to check the solenoid resistances?
I will pm my email for the resistance charts.

Cheers

Click to expand...

No need to pull the sump, you can check the solenoid resistances at the ECU connector under the LH seat which will also effectively check the connector at the box.
It's also worth checking the transfer box ECU as that can affect the auto box function. Select low range and see if it works. The Transfer ECU's are prone to burning out, often due to the transfer select motor seizing.

Cheers Datatek

i haven't had any problem with the transfer box, to date, but i will check out the plug and electrical connections.

Thanks for the email with the wiring diagram and the solenoid function. I will print them off and do some electrical testing tomorrow. My guess is it's the torque converter lock up solenoid thats playing up (i hope).

I picked up a 2nd hand auto trans for $50 (25 quid) off of our native ebay, which in my opinion is a hell of a bargain as it's probably worth that in scrap metal, so i should be able to rob some parts from that if i need them. Although nothing ever seems to be that simple.

spadgr said:

Thanks for the email with the wiring diagram and the solenoid function. I will print them off and do some electrical testing tomorrow. My guess is it's the torque converter lock up solenoid thats playing up (i hope).

I picked up a 2nd hand auto trans for $50 (25 quid) off of our native ebay, which in my opinion is a hell of a bargain as it's probably worth that in scrap metal, so i should be able to rob some parts from that if i need them. Although nothing ever seems to be that simple.

Click to expand...

You would be better swapping the complete box unless you know what you are doing. The valve block is full of little springs of different rates and other bits that will fall out.

The box is out of a V8 petrol so the valve block, i assume, will have differences, though i am hoping the solenoids are the same.

I think i would be capable of carefully swapping over the solenoids, if the need arises, but if it does become too technical then i will take it to the local auto box expert.

Cheers

4HP22 was fitted to both the Diesel and the 4.0 petrol so I assume the valve blocks are the same...

The 4.6 used the 4HP24, so I don't think you can fit to the Diesel

I just checked up on the auction and it is apparently out of a 1996 4.7. I will go and have a looksee and make a decision when i get there. If i have to buy it and it's no use to me then i will just flick it on.

Cheers Datatek,

Are all the electrics the same? i.e. ecu and all that still the same?

is the diesel torque convertor all have the same height , the deep ?

spadgr said:

Cheers Datatek,

Are all the electrics the same? i.e. ecu and all that still the same?

Click to expand...

I have yet to do it myself, but others have done it. The electrics are the same, the only differences are the bell housing, torque convertor and the overall length, the length is sorted by the spacer fitted at the rear on the 24. You use your existing auto ECU, the P38 auto ECU for the 4.6 is not compatible.

what about different from the 4hp22 and the 4hp24


ratio 1 , 2 . 3. and the P gear;;;;;;;;

I have been told lead to believe that the valve body from a petrol auto and a diesel auto are different. Does anybody know if that is true?

spadgr said:

I have been told lead to believe that the valve body from a petrol auto and a diesel auto are different. Does anybody know if that is true?

Click to expand...

as the 4.0 Petrol and the 2.5 Diesel both used the 4HP22 I would think the Valve Block is the same!

The 4.6 used the 4HP24 and I would assume the Valve Block would be different!

Saint.V8 said:

as the 4.0 Petrol and the 2.5 Diesel both used the 4HP22 I would think the Valve Block is the same!

The 4.6 used the 4HP24 and I would assume the Valve Block would be different!

Click to expand...

Valve block is the same functionally on the HP24 as the HP22, gear ratio's are also the same according to my info.

if the gear ratio is the same ; we can build the gear box from the 4hp24 to 4hp22 the only problem now is the Torque converter depth in mm ..... will this also work for the 4hp24 :::::::depth in mm


this table is only for 4hp22 from ashcroft

Box Code.....................Depth in mm

061.................................. 22

064....................................22

065....................................27

332....................................51

593....................................51

699....................................51

727....................................27

728....................................83

740....................................51

741....................................51

742....................................51

744....................................18

748....................................18

747....................................27

757....................................27

759....................................27

763....................................83

764....................................27

765....................................27

766....................................96

767....................................27

768....................................83

769....................................83

773....................................96

I mean will it work for the 4hp22