Fault code P0705 Advise please

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kgeddes

Active Member
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Location
Dunoon, Argyll
Advise please on the following:

Just bought a 2002 L322 V8 with LPG.

Recently got TRANS FAILSAFE PROG message before starting the engine. Engine started ok and it ran perfectly for 35 miles. When I got home put transmission into park and got message again. Played about with the selector for a while going from drive to park and eventually got the message to come up again. Vehicle very slow to take off (presume in 3rd or 4th).

Everything fine for next two days. Took it to garage got battery and alternator checked, all ok (new battery fitted last week). Got codes read, showed up P0705 TRANSMISSION RANGE SENSOR CIRCUIT MALFUNCTION (PRNDL INPUT). Fault code cleared. All ok for last couple of days.

I will check the connections etc but if all ok do I need part number UHB500020?

Thank you.
 
Yes, that’s your inhibitor switch (or its wiring) playing up. You can test it by checking that the continuity between the +ve pin and the remaining four pins follows the sequence in the table (ignore gear positions 4, 3 & 2 as they aren’t used for the Range Rover)

InhibitorSwitch1.jpg


InhibitorSwitch2.jpg


InhibitorSwitch3.jpg


(The switch logic specified in the workshop manual is incorrect, by the way)
 
Bemble said:
Yes, that’s your inhibitor switch (or its wiring) playing up. You can test it by checking that the continuity between the +ve pin and the remaining four pins follows the sequence in the table (ignore gear positions 4, 3 & 2 as they aren’t used for the Range Rover)

had the same problem with mine when I first had it got this switch changed & gearbox still failed :confused:old switch still in the bottom of my rollcab incase
Click to expand...
 
wil2813 said:
was putting up trans failsafe regular one day just slipped a lot & went straight into top gear with a loud bang then wouldn't drive only crawl £2150 later all is good mind you that was 3 years ago
Click to expand...

Was the car moving when you kept getting the FAILSAFE messages before the loud bang? I am getting the message sometimes but only when stationery and selecting PRND. Thanks
 
Bemble said:
Yes, that’s your inhibitor switch (or its wiring) playing up. You can test it by checking that the continuity between the +ve pin and the remaining four pins follows the sequence in the table (ignore gear positions 4, 3 & 2 as they aren’t used for the Range Rover)

InhibitorSwitch1.jpg


InhibitorSwitch2.jpg


InhibitorSwitch3.jpg


(The switch logic specified in the workshop manual is incorrect, by the way)
Click to expand...

I have located the inhibitor switch on the gearbox ok but where is the connector C1452 located please? I assume at the back of the engine but can't get in there to see :(
 
It’s attached to a bracket bolted to the top of the bellhousing. You’re best to remove the heater plenum to provide access.

PlenumChamber_zps1d5a7031.jpg
 
On BMWs (and Jaguars) fitted with the 5HP24 the connector and its bracket are bolted to the bottom of the oil pump housing, making access much easier :

E53inhibitorswitch.jpg


Presumably Land Rover thought it was too risky to have it positioned down there (wading, off-road damage, etc.) and so moved it to the top of the bellhousing. This meant that the switch had to be fitted with longer wires, thereby ruling out using a BMW switch on the L322 (even though the switch part & the connector is identical). The photo below shows the BMW X5 switch alongside the Range Rover one.

Inhibitorswitchcomparison_zps021886ab.jpg
 
Thank you again for the excellent information.

When I am removing the air intake plenum must I disconnect the battery negative terminal? I am concerned about the bolt on the right connecting the +ve cable.

Thanks again!
 
Bemble said:
On BMWs (and Jaguars) fitted with the 5HP24 the connector and its bracket are bolted to the bottom of the oil pump housing, making access much easier :

E53inhibitorswitch.jpg


Presumably Land Rover thought it was too risky to have it positioned down there (wading, off-road damage, etc.) and so moved it to the top of the bellhousing. This meant that the switch had to be fitted with longer wires, thereby ruling out using a BMW switch on the L322 (even though the switch part & the connector is identical). The photo below shows the BMW X5 switch alongside the Range Rover one.

Inhibitorswitchcomparison_zps021886ab.jpg
Click to expand...

Would it not be possible to use the BMW switch and just extend the wires with fly leads and make suitably robust, weather proof connections?
 
I don’t see why not. These switches go for silly money on eBay (typically £150-£200 for one that’s already been under a vehicle for 10 years, new ones are over £400) which is all the more reason to test the switch & wiring first before spending money on a replacement. The Jaguar switches have a different connector.
 
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