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bbjunkie

New Member
50 miles from home, and with a trailer on the back of my P38A 2.5DT (Manual Transmission)..

Stopped to unload the trailer, when I got back in and went to drive off the Range Rover was in low range.

No matter what I tried it didn't make a difference. At one stage the message centre told me I was in High range, but in actual fact it was still low. Other messages that came up were "Select Neutral" and "Slow down"

Long story short, after a 2.5hr drive home in the middle of the night to avoid traffic I got a look - three out of the five field effect transistors inside the Transfer Box ecu appear to be blown (see photo)

Question,

Do these just blow? I am considering removing the ratio motor to see if it has jammed and therefore caused a large current surge. I have replacement transistors ordered, but don't want to blow the new ones!

Suggestions welcome

Thanks

bb
 

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You should test the transfer motor, it's possible in situ with Battery.

Solder tip: cut the legs of the Mozfet's on the top (not much room) and pull them out one by one with the heat on.

When i fixed my ecu the transfer motor was fine and haven't had a problem since
 
You can test the motor with just a battery, the two big contacts on the t/motor connector are the positive and negative pole, reversing them just reverses the motor direction. Mind you, that the motor is limited in it's travel, IIRC about two seconds from one side stop to the other.

If you haven't done anything with the motor, before the ECU burnt out, i'd suspect the ECU, but if you played with the low range recently (half hour) before the incident, it is possible that the stator in the motor started chipping and blocked the rotor. I'd check the motor anyway, it's dead easy.
 
About 20 minutes before I had been using low range, shifted to high range then accidentally pressed the low range switch instead of the hazard warning lights switch - instantly I then pressed it again to go back to high (probably before the motor had finished it's travel to low).

Perhaps this caused an overload? I'll check the motor just in case.

bb
 
Do check the motor :) the stator part of the motor is known to chip. Just clean out the chipped parts, brush it a bit so you remove all the residual parts and reassemble. Mine works like that for a year now, without any problems.
 
Just tried sorting this by removing the motor to test... damn am I sorry I started. Got the bolts out only to find the handbrake housing is in the way :(

RAVE says, and I quote:
1. Raise vehicle on four post lift.
2. Disconnect battery negative lead.
3. Disconnect temperature sensor.
4. Disconnect motor multiplug.
5. Remove 4 bolts securing motor to transfer gearbox.
6. Remove motor.

However, from what I can see the motor doesnt just drop down when the bolts are removed, it needs to be pulled out of the transfer box (toward the rear of the vehicle) however this cant be done with the handbrake assy in place.

Broken the gasket seal between motor and transfer box, so no going back, the motor MUST come out.

Am I missing something? Perhaps it's the position the motor was left in by the faulty ECU ? What's the next step? I assume disconnect driveshaft, remove guard and drop it down then remove handbrake housing assy?

The least steps possible, I budgeted 2 hours out of my weekend for this job and if it takes much more i'll need to leave til next weekend :(
 
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Might be different on mine i managed to wriggle it out to check it when dealing with the issue, nothing else had to come off.
Sure you got the bolt in the end off? of-course you have, silly me...:)
 
Druim said:
Might be different on mine i managed to wriggle it out to check it when dealing with the issue, nothing else had to come off.
Sure you got the bolt in the end off? of-course you have, silly me...:)
Click to expand...

DSCF5275.jpg
[/IMG]
 
Thanks for the quick reply, and a fountain of knowledge as always!

Motor is out, and is totally toasted.

Could a failure in the transfer box cause this? When I opened the motor there was some foul smelling sticky brown watery type liquid (very like stale petrol) that leaked out.

Once opened it was clear to see that the windings on the armature are burnt out.

I don't want to just stick a new motor and transistors in until I have an answer on what caused this chain of events.

The face where the motor mates with the transfer box is spotlessly clean, aside from some black silicone gasket (is this standard, or has someone been there before me?)

Thanks again

Pete
 

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bbjunkie said:
Thanks for the quick reply, and a fountain of knowledge as always!

Motor is out, and is totally toasted.

Could a failure in the transfer box cause this? When I opened the motor there was some foul smelling sticky brown watery type liquid (very like stale petrol) that leaked out.

Once opened it was clear to see that the windings on the armature are burnt out.

I don't want to just stick a new motor and transistors in until I have an answer on what caused this chain of events.

The face where the motor mates with the transfer box is spotlessly clean, aside from some black silicone gasket (is this standard, or has someone been there before me?)

Thanks again

Pete
Click to expand...

That will be water ingress, get another one, would be my suggestion and with ecu repaired you should be all good
 
Thanks Druim

One other thing I forgot to mention, when removing the motor I noticed that when I removed the bolts that the motor wanted to spring anti-clockwise (down) and to refit the bolts I would have to force it back up (clockwise)

Is this normal?
 
bbjunkie said:
Thanks Druim

One other thing I forgot to mention, when removing the motor I noticed that when I removed the bolts that the motor wanted to spring anti-clockwise (down) and to refit the bolts I would have to force it back up (clockwise)

Is this normal?
Click to expand...

When i took mine off it didn't do that
You should be able to select Hi - N - Low by hand tool now you got it off and check transfer box are alright - last oil change when?
 
Wasn't aware the oil needed changing! - I've owned it 4 years and have done approx 8000 miles in that time, it's a workhorse for pulling my boat and trailers.

Will try shifting into neutral / high and see what happens.

Is it safe to drive it forward with the motor removed to check the transfer box is ok?

Obviously there's a big hole there, so I wouldnt be taking it out on the road.

Would a pair of vice grips be the most suitable tool to grip the shaft and turn it?
 
bbjunkie said:
Wasn't aware the oil needed changing! - I've owned it 4 years and have done approx 8000 miles in that time, it's a workhorse for pulling my boat and trailers.

Will try shifting into neutral / high and see what happens.

Is it safe to drive it forward with the motor removed to check the transfer box is ok?

Obviously there's a big hole there, so I wouldnt be taking it out on the road.

Would a pair of vice grips be the most suitable tool to grip the shaft and turn it?
Click to expand...

Pliers/grips or adjustable anything
if its just moving the car it should be okay
Use the same ATF as gb, there no filter for transfer box, loosen filler cap first 1/2" racket fit direct, drain, use blue holymar or like gasket to seal plugs ,
refill think about 2 -2.5 liter until level with fill hole,
bit tricky position to fill - wee pump a big help
 
bbjunkie said:
Thanks!

Have ordered a motor and will change the oil while im at it.
Click to expand...

While you're at it, why not change the gb oil and 2 x diff. oils? Check breathers are ok as well, clear & intact
said earlier to use same ATF in transfer box as in gb, but as yours are manual you would use MTF in gear box, transfer oil should be ATF all models.
Also grease the U/J's and prop shafts with Lithium based grease, need a grease gun for that, 6 nipples in total.
Horrible things can happen for those neglecting the maintenance, bit like a time:boom:
 
bbjunkie said:
Ok, you have convinced me! I'll do that too. What sort of pump do you recommend for dispensing the oil?
Click to expand...

I will probably try my garden hose sprayer without the lance next time, datatek said he used that.
Last time used a helper and a funnel, hose and gravity, bit awkward but worked.

Sure you can buy designated pumps for it, somewhere... Some small oil cans comes with long spout - using that for diff. oil.
 
Druim said:
That will be water ingress, get another one, would be my suggestion and with ecu repaired you should be all good
Click to expand...

So far so good.. got the ECU and motor fitted tonight, drove it out and down the road no problems.

Noticed a small hole in one of the sills when I was underneath, so will get the garage to change the oils when they have it up on the ramp - too much like hassle trying to do it with a trolley jack and axle stands!

Thanks again guys for all the help, saved me a small fortune - make that a large fortune if i'd taken it to a main d(st)ealer
 
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