ABS resistance testing with multimeter

[MartyJ76]

Hi, anybody got any autoelectrical knowledge can help me out? Mitsibushi L200 ABS Light on (centre diff flashing, Traction Control lights etc.). Put multimeter to each ABS sensor and got 623, 623, 623 ohms all round, except front left which is 619 ohms. Is this small difference enough to tell me sensor needs replacing? Obviously wiring is aok, Ive cleaned all of them up individually but no change. No fault code on cheap OBD scanner. Any ideas be much appreciated

[Richard-D]

MartyJ76 said:

Hi, anybody got any autoelectrical knowledge can help me out? Mitsibushi L200 ABS Light on (centre diff flashing, Traction Control lights etc.). Put multimeter to each ABS sensor and got 623, 623, 623 ohms all round, except front left which is 619 ohms. Is this small difference enough to tell me sensor needs replacing? Obviously wiring is aok, Ive cleaned all of them up individually but no change. No fault code on cheap OBD scanner. Any ideas be much appreciated

How have you determined the wiring is ok?

No, that difference is not enough to confirm the sensor has failed.

The real answer is a better diagnostic scanner, which will allow you to see the fault code in the ABS ECU and to do a live reading of all the sensors whilst driving. Assuming the fault is in an ABS sensor (big assumption) you can then jumper to the opposite side to confirm if the fault is in the sensor or car's loom.

[MartyJ76]

Thanks Richard. I really appreciate this, at least prepares me for the next stage. I presumed since each sensor is reading something, then the wiring for each sensor, as opposed to the loom further on, must be intact (each one seems seemingly undamaged). Have ordered a replacement sensor for the one with a few less ohms, in hope if nothing else. Next stop garage for acute electronic diagnosis if no joy.

[Richard-D]

No problem. I see what you were saying, that the wiring in the sensor loom is ok, not that the wiring in the rest of the car is good.

Although you may get lucky I wouldn't go swapping parts yet. Diagnostic scanners are not expensive nowadays and swapping parts can often introduce more faults, complicating the issue.

[richs2891]

Are you sure the battery is OK, and not too old ? I had a 2004 shogun and that threw random numerous faults ABS and traction control faults, eg lights on the dash, all went away when I replaced the orig (8 year old) battery. Odd thing was it always started ok, but would be a slow starting if it had sat for a week.

[E-bmw]

MartyJ76 said:

Hi, anybody got any autoelectrical knowledge can help me out? Mitsibushi L200 ABS Light on (centre diff flashing, Traction Control lights etc.). Put multimeter to each ABS sensor and got 623, 623, 623 ohms all round, except front left which is 619 ohms. Is this small difference enough to tell me sensor needs replacing? Obviously wiring is aok, Ive cleaned all of them up individually but no change. No fault code on cheap OBD scanner. Any ideas be much appreciated

Does your code reader do "live data"?

If so, plug it in, get it set up to read wheel speed & take it for a drive, they should all be reading the same.

[MartyJ76]

Grateful for all of these suggestions. I've tried a new sensor to replace the one of the four reading lower ohms today. To no avail, and as suggested above has just confused matters in that being a different manufacturer, it reads even lower ohms altogether when fitted. I am now wondering if the ABS control unit reads any differentiation in resistance and automatically throws the light on?

My reader does indeed do live data (thanks for the suggestion hadnt thought of this) but refuses to measure wheel rotation so I think another trip to the garage is due.

Its a nuisance in as much as the ABS light on doesn't seem to have disabled the ABS it's behaving entirely normally on hard stops. Smooth thudder thudder jolt jolt as always when stopping on rough or slippy ground. Front pads and discs are all new (after the light came on), the reluctor/tone rings all seem in good shape and clean (they are inside the shaft on the rear so not exposed).

Its strange in as much as initially the light would come on and go out intermittently but not often, and there was some vague grinding/clicking/crunching feedback through the brake pedal not always with the ABS light on. Then the light problem gradually became more regular within a fortnight and is now permanent. Yet the clicking feedback has disappeared (prob something to do with pads and discs now replaced but seemed contingent with the ABS light problem.

Will keep in mind the battery suggestion, I've had electronic issues with vehicles before resolved by battery replacement, often with a battery reading good after drop test. As a consequence of recent visit to a certain unnamed national tyre centre I was informed I'd been given a free vehicle checkover no less!.....Battery was reported not to be in 100% health, 2.5% water in brake fluid, and also informed I had a cracked leafspring. Crack was reportedly right up the centre of the leaf, front to back as opposed to a crack halfway a long. There's me thinking ' Phew Its so good these people have got my back!!' Since am in process of having chassis undersealed I took it upon myself with the guy who's spraying it to inspect......no such crack. Unless they have used X ray, dye pen and vac box equipment revealing subsurface structural issues unbeknown to me, then I am absolutely sure there is no crack. However I will def keep the battery in mind to have checked when I book it in.

Thanks so much all, I will make an effort to post a follow up if its resolved as, at least for me, so many historic posts prove so useful!!