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Discussion Starter #1
So I have a 2003 range rover HSE, 156k miles, I have fallen victim to the trans failsafe prog. My vehicle can be driven shortly (maybe 20 min) before it is sent into limp mode, it seems it is fine when the vehicle is cold but as soon as she warms up the trans failsafe prog comes on. It is also worth mentioning the transmission seems to be shifting fine, and the previous owner had it serviced regularly at Aamco.

I have checked the transmission fluid, and it is full, slightly dirty but not in need of a change.

I have also replaced the Neutral Position Switch, I went even further to replace the transfer case motor/potentiometer.

It seems none of these were the issue, so I am left with some extra parts, and I have ordered an ALL COMMS code reader which should be arriving in maybe a week or so. I am definitely not taking it to the stealership, so without the codes I am kind of dead in the water, maybe it's worth the speculation but what else could it possibly be, I am left scratching my head here ?
 

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Blocked transmission cooler? It’s at the bottom of your radiator. Or possibly the radiator itself is blocked. The bottom section is what cools the transmission via that cooler.
 

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LEGACY VENDOR
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It’s likely to be the issue which is by far the most common cause of failure on the 5HP24. The B-clutch hub/C-clutch drum axial bearing has failed and the O-ring on the input shaft/A-clutch drum has split, as a result. Does the transmission failsafe to 5th gear rather than (the default) 4th gear?









Phil
 

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Discussion Starter #4
I was under the impression that it was stuck in third gear. Maybe it is fourth. the trans cooler is working fine but I'll take another look and see, I am not getting a heat warning in the dash, just trans failsafe. It could very well be a bearing as we know when metal heats up it expands.

In order to replace this bearing I'll have to drop the trans?
 

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Although the failed/worn bearing is responsible for the issue, the actual cause of the failsafe message is the resulting split O-ring, which allows fluid pressurising the A-clutch to escape and the clutch therefore slips.

When the fluid is cold, the increased viscosity means that the pump can keep up with the leakage and maintain pressure on the clutch. Once the fluid gets hot, the leakage exceeds the pump's capability, the pressure drops and the clutch slips.

The A-clutch is used in 1st, 2nd, 3rd & 4th gears so the control system has no choice other than to select 5th gear to ‘get you home’. If your transmission is failing safe to one of the other forward gears, this is not what’s causing your problem.

The transmission has to be removed from the vehicle and disassembled to replace the bearing and the O-ring.

ZF 5HP24 teardown

Phil
 

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2002-2005 Range Rover MkIII / L322
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If you are sure it is stuck in 3rd gear during failsafe, i would suggest the transmission oil cooler is blocked on coolant side or bottom of radiator which cools the transmission oil is clogged. I had that same issue a several years ago. The previous owner put stop leak in and it started to gunk up the coolant side of the oil cooler. Failsafe mode in 3rd is the transmission computer keeping the revs up so the transmission oil pump can pump more fluid to cool it down, IIRC. I replaced the oil cooler and all was well. I ended up replacing the radiator shortly after that during a water pump replacement.

If it goes into 5th gear during failsafe, it is most likely the axial bearing and o ring failure mentioned above by RRPhil. I too had that happen to me 2 years ago.

Ryan
 

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Discussion Starter #7
Thanks for the input guys, I don't think it's going into 5th gear, I think its 3rd or 4th. If it was starting in 5th that would be a real tough start from a dead stop. I will look into the oil cooler when I get some extra time to work on it, if that is the case I could probably just clean the gunk with solvent at school.

Hopefully my tuner shows up soon, I will post the codes that are coming up ?
 

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Discussion Starter #8
Update here, I have discovered slight coolant leak, looks as though the previous owner had put the wrong coolant (green) it is leaking from the fill hose, not the trans cooler. Is it possible the wrong coolant could be setting off trans failsafe? From what I understand these rovers use the blue coolant? If this is the case I plan on doing a coolant flush. Hopefully clean the gunk from the system.

To confirm 70mph at around 3000 rpm, is this is 3th gear ?
 

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To confirm 70mph at around 3000 rpm, is this is 3th gear ?
That corresponds with 4th gear, which is the default limp-home gear for the 5HP24 (3rd gear would be nearer to 4500rpm at 70mph). It’s not always easy to match the engine and vehicle speeds to a particular ratio in failsafe mode as the torque converter is automatically unlocked. 5th gear (with the LUC engaged) would be around 2400rpm at 70mph.



Phil
 

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Discussion Starter #10
It seems I have found the issue.... the coolant hose from the overflow tank to the transmission thermostat has been rubbing against the fan belt. part NO: PCH001130
it seems another mechanic decided to cut the hose in the damaged area, and put a coupling with hose clamps on, instead of replacing the hose with the proper part. also noted the hose was not properly fastened down, which is why it has been rubbing against the belt... IMO this coupling is restricting the coolant to the trans cooler. I have ordered a replacement part will report back once I have replaced the hose.
284585
 

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Discussion Starter #12
I have found this oil cooler here

my question is does this come with the O rings on the coolant side? or should I probably order them
 

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Discussion Starter #13
I suppose I could remove to cooler and clean it with kerosine or naptha, that should remove the calcium deposits, just soak it for an hour, then compressed air to clean
 

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I have a similar problem, I posted this the other day. I don't seem to have any leaks, when I select d it jumps into gear and goes up the gears very quickly to 5th (I believe)

Hunh8er
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Hi all, I have done a search under the title and nothing was found, I desperately need help.
My 2003 l322 vogue is stuck in limp mode whilst being stuck in low range. Has anyone come across this before, and if so, what was the solution? The car would do about 30 mph at 2500 rpm.
Thanking you in advance
Jp
 

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It seems I have found the issue....
I still don’t see how a coolant problem would generate the failsafe condition. If the transmission fluid starts to overheat, the controller inhibits upshifts to hold the transmission in the lower gears to keep the engine speed high (& therefore the fluid flow through the cooler at its maximum), but it doesn’t put the transmission in failsafe. If the fluid temperature continues to rise then the message centre will display TRANSMISSION OVERHEAT but, again, it doesn’t put the transmission into failsafe mode.

Phil
 

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Discussion Starter #16
I still don’t see how a coolant problem would generate the failsafe condition. If the transmission fluid starts to overheat, the controller inhibits upshifts to hold the transmission in the lower gears to keep the engine speed high (& therefore the fluid flow through the cooler at its maximum), but it doesn’t put the transmission in failsafe. If the fluid temperature continues to rise then the message centre will display TRANSMISSION OVERHEAT but, again, it doesn’t put the transmission into failsafe mode.

Phil
Yeah certainly a strange problem, I am stuck in 4th gear with the failsafe. I have not seen trans overheat message at all, but once the car gets up to temperature (after about 15-20 minutes) is when the message is displayed. you were saying the bearing/ o-ring issue would default to 5th gear failsafe?

I have installed the replacement hose, and will be flushing the remainder of the coolant tomorrow, will put the proper blue BMW coolant.and post update here.

it could very well be the neutral switch? I rebuilt my neutral switch, drilled the rivets, cleaned it and used Dielectric greese. but was still having issues after putting it back on (this was before the leak)
I was convinced this was the issue, after Rebulding It, and still having issues, I went and got a replacement from pick a part, it was from a 2004 range rover, and that is what I am using currently.
 

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Discussion Starter #17
284866


I Have fixed the faulty hose and flushed green coolant then put in blue, did not replace the trans cooler, it doesnt seen to be clogged or have any buildup. I am still having trans failsafe, I am now able to confirm that it is in fact 4th gear (tested out driving in manual mode, thinking that would make a difference, but the trans failsafe never fails to happen)
I'm thinking this could be a transmission solenoid?
 

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Discussion Starter #19
So now we need the error code that caused the failsafe, which will be stored in your controller.

Phil
Yeah, Still Waiting on the code reader, I think there is some sort of issue with my order I've contacted the seller, will update the thread once I have some codes !
 
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