Wheel Speed Sensor Output

MonsterRepairMan

Member

Posts

26

Location

Norwich

• Jul 10, 2019

• #1

Discovery 2 2002 TD5. Like a lot of other people I have the 3 Amigos. I have been told that the left front sensor is the problem by local garage.
I have tested the voltage output of the sensors which is 1.1 volts ac accept the left front which is 0.225. (All checked at the same speed) Continuity is around 1100 ohms for all sensors, with no leakage to ground. Can I assume that a faulty wheel bearing is causing the low output from the left front sensor? I do not have access to Hawkeye.

 

sierrafery

Well-Known Member

Posts

17,911

Location

Arad/Romania

• Jul 11, 2019

• #2

Yes, as long as the resistances are the same then most probably the problem is with the hub cos the air gap is affected by the play in the reluctor ring

 

MonsterRepairMan

Member

Posts

26

Location

Norwich

• Jul 11, 2019

• #3

Thank you Sierrafery,
We have removed the sensor & found damage to the tip, also 2 shims had been fitted to space it out. We fitted a replacement sensor & tried to space it out, clear of splines. Still getting low output. We have ordered a new hub.

 

MonsterRepairMan

Member

Posts

26

Location

Norwich

• Jul 22, 2019

• #4

We have now replaced the hub but the 3 amigos are still on. We will have to get the DTC's read again.
Previously we had a shuttle valve fault code, we checked the mod that had been done & fitted better quality heat shrink connectors but there could still be a problem there.

 

sierrafery

Well-Known Member

Posts

17,911

Location

Arad/Romania

• Jul 22, 2019

• #5

This is not something to fix without a proper diagnostic tool cos there are cases when the ECU memory is full with logged hystorical codes then the warnings will stay on untill the codes are cleared from the memory even if there is no current one.

 

ronsealdeath

Sagging Member

Posts

1,851

Location

Swansea, Wales

• Jul 25, 2019

• #6

What hub did you use? Suggest a wabco genuine hub is the only way to guarantee a fix as aftermarket hubs can be poorly made. I know they are expensive but it is a critical part.

 

MonsterRepairMan

Member

Posts

26

Location

Norwich

• Aug 5, 2019

• #7

No way can we afford genuine parts. We got it on ebay. I have checked the wheel speed sensor output again. This time the left hand front is 3.20volts ac. The others are still around 1.1volts ac. Why is the left hand front sensor now reading higher than the others??????
Any advice greatly appreciated.

 

sierrafery

Well-Known Member

Posts

17,911

Location

Arad/Romania

• Aug 6, 2019

• #8

How did you test the AC voltage? by turning the wheels at the same speed and measuring in the sensor's plug? it's well known that cheap hubs from ebay can have he wrong number of teeth on the reluctor ring or unreliable sensors also checking that voltage with multimeter while you are not 100% certain that the wheel is turning with the exact same speed can be irrelevant as the multimeter can give strange readings with small differencies cos the AC scale is calibrated for steady 50Hz while the frequency of the sensor's output is speed dependant... as i said the D2's ABS system is not something you can accurately diagnose without dedicated tester

 

MonsterRepairMan

Member

Posts

26

Location

Norwich

• Aug 26, 2019

• #9

sierrafery said:

How did you test the AC voltage? by turning the wheels at the same speed and measuring in the sensor's plug? it's well known that cheap hubs from ebay can have he wrong number of teeth on the reluctor ring or unreliable sensors also checking that voltage with multimeter while you are not 100% certain that the wheel is turning with the exact same speed can be irrelevant as the multimeter can give strange readings with small differencies cos the AC scale is calibrated for steady 50Hz while the frequency of the sensor's output is speed dependant... as i said the D2's ABS system is not something you can accurately diagnose without dedicated tester

Click to expand...

We have bought a Foxwell NT520, checked the DTC's & found shuttle valves open circuit. After replacing the shuttle valves & carrying out the on-line mod, cleared all DTC's, none have returned & 3 amigos out at last. Is it safe to assume that the new hub we fitted must have the correct number of teeth on the reluctor ring???????