L322 RR speedometer stopped working, not fuse

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Alan Ross

Member
Posts
23
Location
Lanark
- 'ABS / HDC Inactive' dashboard message came on last week, day after I had to go thru a large puddle so think it may be sensor at wheel arch again
- y’day red battery light came on even thou battery was charged & showed full charge on trickle charger b4 I left home. On way home (about 200 yards from home) the radio cut out & speedometer stopped working)
- 2day car cut out & wouldn’t start without a jump. Had to jump it numerous times a kept cutting out b4 I could close bonnet. Only travelled about 100 yds when cut out completely & no electrics at all
Any thoughts?
 
- 'ABS / HDC Inactive' dashboard message came on last week, day after I had to go thru a large puddle so think it may be sensor at wheel arch again
- y’day red battery light came on even thou battery was charged & showed full charge on trickle charger b4 I left home. On way home (about 200 yards from home) the radio cut out & speedometer stopped working)
- 2day car cut out & wouldn’t start without a jump. Had to jump it numerous times a kept cutting out b4 I could close bonnet. Only travelled about 100 yds when cut out completely & no electrics at all
Any thoughts?
Welcome,is the alternator charging? These cars are temperamental to low volts;)
 
I have had problems with that one b4, seems to go faulty if I go thru water
I don't know what the set-up is on the L322, whether it's magnetic tone ring on the wheel bearing or a driveshaft mounted segmented ring on the driveshaft, it's possible to be that as much as you think only in sensor terms, the sensor is only a transducer and needs operational tone rings for it to function.

If the sensor checks out ok then look at tone ring.

Most tone rings generate an tiny AC voltage (1-2 millivolt) when in working order, recently discovered a fault tone ring on a car that was the magnetic tone ring on wheel bearing type, bearing not noisy but tone ring kaput.

I checked the opposite side first to prove this and indeed the good side produced 1 millivolt.
 
Straight from Rave

Speedometer
The speedometer is an electrically driven, analogue instrument for displaying the vehicle speed. The pointer needle
is oil damped to prevent impacts on the vehicle wheels, causing deflection of the pointer needle.
The speedometer is driven by a square wave signal derived from the ABS ECU. The wheel speeds are measured by
sensors reading rotational speed from toothed targets on the hubs. These speeds are passed to the ABS ECU in the
form of pulsed signals. The ABS ECU is programmed that 48 pulses is equal to one revolution of the wheels and this
equates in distance to approximately 2 metres. The actual signal that drives the speedometer is a buffered signal sent
from the left hand rear speed sensor.
This information is passed from the ABS ECU, on a hardwired connection, to the instrument pack and is received by
one of the microprocessors. The microprocessor applies a formula to the signal and calculates a numerical, 16 bit
value for the signal. This signal is then used by the speedometer drive to display the current speed to the driver. A
second digital signal output is also broadcast on the CAN, I and K buses for use by other systems.
To prevent incorrect readings due to spinning wheels, the microprocessor introduces a time delay on the output signal
if the received speed signal increases too quickly. The delay ensures that only the true speed is displayed and
transmitted on the bus systems.
Two versions of the speedometer display are used. One shows the speed in kilometres per hour and the other shows
the speed in miles per hour as the main display and kilometres per hour as a secondary display.
 
- 'ABS / HDC Inactive' dashboard message came on last week, day after I had to go thru a large puddle so think it may be sensor at wheel arch again
- y’day red battery light came on even thou battery was charged & showed full charge on trickle charger b4 I left home. On way home (about 200 yards from home) the radio cut out & speedometer stopped working)
- 2day car cut out & wouldn’t start without a jump. Had to jump it numerous times a kept cutting out b4 I could close bonnet. Only travelled about 100 yds when cut out completely & no electrics at all
Any thoughts?
 
What year?

Do you have that stupid piro connection at the positive battery terminal or the mega fuse 1.

remember reading that the piro ones did something like that.

J
 
THANKS EVERYONE. My very nice LR mechanic has called and set my mind at ease & agreed with u’s…..likely to be faulty ABS sensor &/or ring tone. Car cutting out was prob due to battery being very low & not enough power to operate everything needed to keep car running. I haven’t been giving car a long run regularly and been sitting on drive not being used or not plugged into trickle charger for over a week. Hopefully battery will b fully charged by 2moro morning.
 
What year?

Do you have that stupid piro connection at the positive battery terminal or the mega fuse 1.

remember reading that the piro ones did something like that.

J
2004 3.0D Vogue. Not mechanically minded so no idea, but think factory-fitted leads still on it. Does this help?
 
Last edited:
What year? Always good to mention year and engine type.

But as you seem to be on a good path for fixing let’s see how you get on.
A full charged battery might actually fix all your problems anyway;).

J
 
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