abs fault

robdrinky · Post by **robdrinky** » Tue Jan 22, 2008 3:04 pm

Our p reg 4wd bongo has developed a fault with the abs.the warning light comes on sometimes after starting.i have inspected the wheel sensors and found no signs of damage.
i have been offered a 2nd hand control unit for £50(does this seem a fair price),has anyone had a similar problem.
any info appreciated.

further to the replys(thanks by the way),i have only done a visual check of the wheel sensors,i will try to borrow a meter and do electrical checks.
i presume the abs system has a ecu/brain somewhere but on looking through my owners and workshop manual can find no mention of one.

when the ignition switch is turned on the abs light goes out about the same time as the glowplug light but comes back on after a few seconds.however it rarely comes on in the morning(go figure).once on it remains on.

BongoMTBer · Post by **BongoMTBer** » Tue Jan 22, 2008 3:13 pm

When you say inspected, do you mean a clean and electrical continuity check on each sensor?

Does the light come on and stay on when the ign is switched on or does it come on again, normally after moving off?

Have you checked all the connections?

If by control unit you mean the pump/modulator, these very rarely go wrong, it is usually just a sensor.

Ralph · Post by **Ralph** » Tue Jan 22, 2008 3:15 pm

Not looked at a abs Bongo but fixed a Ford just by
unplugging and plugging back in the relays.

bigdaddycain · Post by **bigdaddycain** » Tue Jan 22, 2008 3:18 pm

Hi Rob,The sensors could still be buggered...Remove the plug from the sensor,and test the sensor with a multimeter,if any of the sensors show no resistance,then that'll be the busted one....

You can check the replacement sensor with the same method rob... (if that's the problem of course...)

BongoMTBer · Post by **BongoMTBer** » Tue Jan 22, 2008 3:28 pm

If you want to test each sensor and the loom effectivley, locate the relevant wires for each sensor at the main plug into the modulator/pump unit.

Test each sensor at that point and you will be checking most of the sensing wiring. I think the resistance on my Corrado was around 1000 to 1100 ohms?

You can also test the generated signal from each sensor by switching the multimeter to volts and spinning each wheel. Again, not sure but I think my Corrado registered about 1 volt?

Anyway, the one that did not work had a high resistance and no output. Interestingly but unsurprisingly, it too came about during a spell of cold damp weather.

Nibs · Post by **Nibs** » Tue Jan 22, 2008 9:10 pm

Hi, I had the ABS light coming on then going off for a period of time, had it checked out by someone who could not find the fault. I asked the members for help and was told that the insulation at the back of the instrument pod is poor. Removed the pod cleaned all the printed circuit reconnected and bingo! all's well. Worth a try.
Cheers Nibs

robdrinky · Post by **robdrinky** » Tue Jan 22, 2008 10:54 pm

thanks all for the information.
my next day off is next monday and i will work on it then,will pass on what i find.

robdrinky · Post by **robdrinky** » Wed Jan 30, 2008 1:18 pm

update-all four sensors have continuity(figures match)also get about a volt output when i spin the wheels as fast as i can.all connectors appear sound.have swopped the relays round and checked the fuses.
ecu unplugged and wires give continiuty through to the sensors,and still got the same problem.
my local garage (usually very good)have no info on interogating the ecu diagnostics,does anyone have knowledge of the flash codes and which pin or pins connect to the abs.
ironically i drove the bongo last night and abs light was on,this morning its not on.perhaps i will get it mot,d in the morning!

MountainGoat · Post by **MountainGoat** » Wed Jan 30, 2008 1:56 pm

My ABS warning light came on for a while last year when I was driving on the single track switchback and hilly road out to Egol on the Ilse of Skye. I mentioned this to the breakdown mechanic who had to come out next morning to give us a jump start at a campsite near Kyle of Lochalsh thanks to the then duff split charging system we had.
He said that I had just been overusing the brakes and that it should be ok now that they had cooled down. The light has not come on again since.

waycar8 · Post by **waycar8** » Wed Jan 30, 2008 6:34 pm

i have had similar too, with the abs light coming on, both times, well once it was raining heavy, then the second time it was when i drove through a deep puddle, in the manual it says this isnt anything to worry about especially in wet conditions.

it also says, if you turn off the ignition then turn it back on the abs light should go off automatically, like a reset, but if it stays on then its got a fault and you should go straight to your nearest mazda dealer