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Is 4.3 V enough to power abs sensors? - Kid Rock - 07-24-2017
Ripped apart all the wire loom from wabco ecu to sensors following volvo's wire diagram. Found the right wires for RR rear axle and have found no real issue with the wires... fixed what little i did see... testing the leads to the sensor now and they all read a flat 4.3 v...
Is 4.3 volts acceptable or is there actually a low voltage problem and not a short?
Update: just checked power supply to ecu, it was 12v --- power coming out is 4.3
Wabco frame mounted ecu pn# 44610607
Thanks in advance
Mid 136 sdi 4 fmi 4
RR sensor Short to ground or low voltage -
RE: Is 4.3 V enough to power abs sensors? - Nostalgic - 07-24-2017
ABS sensors are usually hall effect with 4-5 volts reference. When the windings in the sensor fail, they can short out to ground, but open is more typical. Unplug at the RR sensor and check resistance across the terminals.
RE: Is 4.3 V enough to power abs sensors? - Kid Rock - 07-24-2017
(07-24-2017 )Nostalgic Wrote: ABS sensors are usually hall effect with 4-5 volts reference. When the windings in the sensor fail, they can short out to ground, but open is more typical. Unplug at the RR sensor and check resistance across the terminals.
Not that familar with the hall effect though i did do a quick search on it. It read 1243 ohms resistance which wabco says is in spec? some of the voltage coming out is around 10 then on others its 4.3 (ecu out that is) ... been at this for two days, wires look pretty good. Bad ecu maybe?
RE: Is 4.3 V enough to power abs sensors? - Waterloo - 07-24-2017
Do you have a wiring schematic of the truck. I was having ABS issues and it was the "Compass Module"... Had noting to do with the actual wiring but the module it ran through. Worth a look.
RE: Is 4.3 V enough to power abs sensors? - Nilao - 07-24-2017
Did you test each sensor pin to a ground? Just because it's in range doesn't mean one pin is not shorted.
RE: Is 4.3 V enough to power abs sensors? - Kid Rock - 07-24-2017
(07-24-2017 )Nilao Wrote: Did you test each sensor pin to a ground? Just because it's in range doesn't mean one pin is not shorted.
Thats a good point I'll have to check in the morning. Still testing for ohms in the 900-2000 ohm range? ...On each pin to a good ground ok
RE: Is 4.3 V enough to power abs sensors? - Nostalgic - 07-24-2017
All of my experience is with auto/light truck, but I've had them static test out ok, but when test driving with scan tool hooked up, you could watch it go erratic and drop out (dead open or dead ground). You can hook up a multimeter to it and spin the wheel, but it's next to impossible to make a solid conclusion off of that alone. How much are the sensors? In some cases it's easier to just be a parts swapper. Worst case, you'll have a spare.
RE: Is 4.3 V enough to power abs sensors? - Rawze - 07-24-2017
Replace the sensor if it is old would be my first choice. Next would be to clean up all the plugs and connectors + ensure no pins were tarnished. Then perhaps use an ohm meter on the wires for the circuit while they were disconnected at both ends + check for resistance to ground on each wire. Last would be to disconnect the wiring at both ends completely, ground all pins at one end, then load test the wires with a tail light for a car fed by +12v. Sometimes wires have to be load tested to find corrosion or excess resistance. The brightness of a tail light bulb will often reveal weak connections visually.
RE: Is 4.3 V enough to power abs sensors? - Kid Rock - 07-25-2017
So far replaced sensor, not a thing yet...