P38 no low ratio

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Mudmenance

New Member
Posts
9
Location
West sussex
Morning every JustBrought a range rover p38 as a project its a 2.5hse manual it's being converted to coils but has a problem with low ratio doesn't work I've checked the relays and fuses there's no live to the switch I've check the ecu under the passenger seat it all looks fine ad donsnt smell burnt or anything could it be anything too do with the coil spring conversion with the ecu any help would be much appreciated
 
From what i remember the switches use the earth to switch so there will be no live,
first take of the transfer motor and test on bench if the motor is ok it may well be the neutral switch on the side if the selector housing not getting the in neutral signal as there is a plastic coller on the selector shaft that can move there was a Tech bullitin about it,
a way round this if you dont want to drop the box is unplug the neutral switch and use a link wire to bridge it then try selecting low range in fact try that first.
 
Sorry for late reply havnt managed to get it back in the garage yet due to work but putting it in workshop tomorrow gonna look at the neutral switch and it ifs not get the solinoid motor out but got 3 days of garage time for my self as from tomoz so should get somewhere hopefully
 
The grease in the low/Hi stepper motor can also turn to an almost solid mass which causes it seize, mostly due to lack of use.

Taking it apart and giving it a good service / clean out usually works wonders, it is so rarely used..

Also Between the transfer case ECU and the transfer case shift motor there is a connection in the wiring loom it is buried under the centre console almost directly under the box behind the window switches), where the SRS ECU is located worth checking under there at the connectors as there can be a problem there.

Up to MY 1999 there are 3 connectors there - 2 way Black power to the ratio motor, 10 way White which is the connection between the gearbox and the ECU, and 20 way Black which has the ratio motor position switch wires in it among other things including other gearbox connections

Might be worth having a look there if you have any problems.

Also worth trying to reset the ecu
Turn the key to position 1.
2. Press the throttle pedal to the floor and hold for five seconds.
3. Turn the key to the off position don't remove the key, then release the throttle pedal.
4. Wait at least two minutes for ECU to reset.
5. This will clear the Potentiometer settings and typically allow you to go into low range. If this works, then you need to go between low and high range 3 times. The first is from a dead stop and the second two are while moving around 5-10 miles an hour (you still need to shift into neutral and drive which moving.

H
 
The grease in the low/Hi stepper motor can also turn to an almost solid mass which causes it seize, mostly due to lack of use.

Taking it apart and giving it a good service / clean out usually works wonders, it is so rarely used..

Also Between the transfer case ECU and the transfer case shift motor there is a connection in the wiring loom it is buried under the centre console almost directly under the box behind the window switches), where the SRS ECU is located worth checking under there at the connectors as there can be a problem there.

Up to MY 1999 there are 3 connectors there - 2 way Black power to the ratio motor, 10 way White which is the connection between the gearbox and the ECU, and 20 way Black which has the ratio motor position switch wires in it among other things including other gearbox connections

Might be worth having a look there if you have any problems.

Also worth trying to reset the ecu
Turn the key to position 1.
2. Press the throttle pedal to the floor and hold for five seconds.
3. Turn the key to the off position don't remove the key, then release the throttle pedal.
4. Wait at least two minutes for ECU to reset.
5. This will clear the Potentiometer settings and typically allow you to go into low range. If this works, then you need to go between low and high range 3 times. The first is from a dead stop and the second two are while moving around 5-10 miles an hour (you still need to shift into neutral and drive which moving.

H
The grease in the low/Hi stepper motor can also turn to an almost solid mass which causes it seize, mostly due to lack of use.

Taking it apart and giving it a good service / clean out usually works wonders, it is so rarely used..

Also Between the transfer case ECU and the transfer case shift motor there is a connection in the wiring loom it is buried under the centre console almost directly under the box behind the window switches), where the SRS ECU is located worth checking under there at the connectors as there can be a problem there.

Up to MY 1999 there are 3 connectors there - 2 way Black power to the ratio motor, 10 way White which is the connection between the gearbox and the ECU, and 20 way Black which has the ratio motor position switch wires in it among other things including other gearbox connections

Might be worth having a look there if you have any problems.

Also worth trying to reset the ecu
Turn the key to position 1.
2. Press the throttle pedal to the floor and hold for five seconds.
3. Turn the key to the off position don't remove the key, then release the throttle pedal.
4. Wait at least two minutes for ECU to reset.
5. This will clear the Potentiometer settings and typically allow you to go into low range. If this works, then you need to go between low and high range 3 times. The first is from a dead stop and the second two are while moving around 5-10 miles an hour (you still need to shift into neutral and drive which moving.

H
Thankyou for this will check it all first and get back too you
 
He needs to read old posts if he thinks there's only one funny one on here ;):D
Our mate knows we are all a bit funny on ere':D
IMG_20210214_102242.jpg
 
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