Disco 2 Is my reverse switch faulty?

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bukko

bukko

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Hi all.

My reverse lights don't work and my parking sensors don't come on automatically when I shift into reverse (it's an automatic).
Is there a reversing switch on the auto? Seems sensible to check that first.

Thanks
 
bukko said:
Yes the R comes up. Maybe not the switch then!
Click to expand...
Guess you'll be going under to check the wiring then?
I'd start at where the reverse park sensors meet the reversing light wiring. Also, does your rear window wiper come on when the front wipers are working and you put it into reverse? It should.;)
 
Stanleysteamer said:
Guess you'll be going under to check the wiring then?
I'd start at where the reverse park sensors meet the reversing light wiring. Also, does your rear window wiper come on when the front wipers are working and you put it into reverse? It should.;)
Click to expand...
No, rear wiper doesn't come on.
Also, just had flashing M and S lights, which apparently indicates an electrical fault with the gearbox!
 
bukko said:
I swapped the bulbs of the reverse and fog lights, fog still worked but not reverse so it's not that simple.
Click to expand...
Even if the bulb was blown the parking sensors should still work.
From Rave:
"Reverse gear signal
The feed from fuse 25 in the passenger compartment fusebox is connected to the reverse
lamp switch (manual gearbox), or starter inhibitor/reverse light switch (automatic
transmission), by a GY wire. When reverse gear is selected, the switch closes and the feed
is connected to the ACE ECU, by a GN wire via header C0287 LHD/C0294 RHD, to provide
a reverse gear selected signal. The reverse gear selected signal is used by the ACE ECU
to set the system in a 'locked bars' condition when reversing."

"Reverse Gear
When reverse gear is selected, current from fuse 25 flows across the reverse lamp switch
(manual vehicles only) or the automatic transmission starter inhibitor/reverse lamp switch
(automatic vehicles only) to the PDC ECU on a GN wire. When the PDC ECU receives this
feed it registers that reverse gear has been selected and activates PDC.
PDC Sensors
The PDC ECU provides a feed to connector interface C2403/C2404 on a WG wire, and from
the connector interface to all four PDC sensors on W wires. The sensors are earthed on B
wires to connector interface C2404/C2403, and from the connector interface to the PDC
ECU on a BG wire.
The PDC sensors provide distance signals to the PDC ECU as follows:
The RH outer PDC sensor provides a signal to the ECU on an O wire.
The RH inner PDC sensor provides a signal to the ECU on a Y wire.
The LH inner PDC sensor provides a signal to the ECU on a U wire.
The LH outer PDC sensor provides a signal to the ECU on a G wire.
PDC Speaker
The PDC ECU powers the PDC speaker to give the driver an audible indication of the
distance to an obstacle. The PDC ECU provides the speaker a positive signal on a K wire
and a negative signal on an N wire.
Reverse Gear
When reverse gear is selected, current from fuse 25 flows across the reverse lamp switch
(manual vehicles only) or the automatic transmission starter inhibitor/reverse lamp switch
(automatic vehicles only) to the PDC ECU on a GN wire. When the PDC ECU receives this
feed it registers that reverse gear has been selected and activates PDC.
PDC Sensors
The PDC ECU provides a feed to connector interface C2403/C2404 on a WG wire, and from
the connector interface to all four PDC sensors on W wires. The sensors are earthed on B
wires to connector interface C2404/C2403, and from the connector interface to the PDC
ECU on a BG wire.
The PDC sensors provide distance signals to the PDC ECU as follows:
The RH outer PDC sensor provides a signal to the ECU on an O wire.
The RH inner PDC sensor provides a signal to the ECU on a Y wire.
The LH inner PDC sensor provides a signal to the ECU on a U wire.
The LH outer PDC sensor provides a signal to the ECU on a G wire.
PDC Speaker
The PDC ECU powers the PDC speaker to give the driver an audible indication of the
distance to an obstacle. The PDC ECU provides the speaker a positive signal on a K wire
and a negative signal on an N wire."
 
Could also check these fuses although if the reverse position light on the gear change lever is working this may mean this is unnecessary.
"When the ignition switch is in position II, current flows from the ignition switch on a Y wire to
fuse 25 of the passenger compartment fusebox. Fuse 25 provides a feed to the reverse lamp
switch (manual vehicles only) or the automatic transmission starter inhibitor/reverse lamp
switch (automatic vehicles only) on a GY wire.
PDC ECU
When energised, the auxiliary circuits relay provides a feed to fuse 16 of the passenger
compartment fuse box on a WG wire. Current flows through fuse 16 to the PDC ECU on an
LGO wire. The PDC ECU is earthed on a B wire vie earth header C0707."
 
bukko said:
Also, just had flashing M and S lights, which apparently indicates an electrical fault with the gearbox!
Click to expand...
That can be caused by the XYZ switch too, you need a diagnostic tool to see the stored fault code and the live outputs cos the fact that the R appears on the dash means only that the reverse contact is not completely worn but it can be weak as to not support any load while the BCU can still sense it
 
sierrafery said:
That can be caused by the XYZ switch too, you need a diagnostic tool to see the stored fault code and the live outputs cos the fact that the R appears on the dash means only that the reverse contact is not completely worn but it can be weak as to not support any load while the BCU can still sense it
Click to expand...
That's what I was hoping. Unfortunately my Hawkeye is in my other Disco, currently at a garage with a busted crank. Will go get it this arvo.
 
If you get the P0705 code then the problem is with the switch and it can affect the reverse output too so fix that and if the reverse lights will still not work after that means it's a very strange wiring issue somewhere. If you are up to remove the console you can check directly with a wired 12v/55W(or stronger) bulb as to connect one wire to body and the other to C0668/0681 pin 1(green/brown wire) to see if it lights up or not cos there is direct output from the reverse contact( a multimeter is not so relevant in this case cos it doesnt create a voltage. drop if you see what i mean)
C0668.jpg
 
bukko said:
Not as far as I am aware.
There is a seperate binnacle switch to switch them on manually as well as them coming on when reverse is selected.
This is described in the owner's manual so must be an LR thing.
Click to expand...
My Disco 2 is not the top of the range one, it's a GS 2000 Td5 auto so no refinements like reversing noises!!
 
mrshells said:
Also check the wiring loom from the XYZ switch
it runs over the gearbox and can chafe on the box
mine did this last year and it took me days to find
there is a post somewhere
ill see if i can find it
https://www.landyzone.co.uk/land-rover/more-xyz-or-not.376383/
Click to expand...
Interesting - could that also cause problems with the signal from the fuel tank sender?
Mine seems to be intermittent but I had assumed that was a faulty sender. Didn't occur to be they could be linked until I read your thread.
 
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