Hello,

Have been trying to diagnose an abs fault. Abs light comes on shortly after setting off. Figured this was a wheel speed sensor issue and so have checked (twice) all sensors and then continued to run all tests suggested in the FSM. The only anomaly i can find seems to be the voltage at pin AC of the abs computer. I'm reading 11.5V at idle. According to the alternator section of the FSM terminal L (which is linked to the abs computer) should read between 12.9V and 13.5V at idle. I also notice that the charge light is barely lit with the ignition on but then does go out completely once engine is started. Confident that id found the issue i removed the alternator and had it bench tested by a firm that had previously rebuilt it. They don't think the alternator is at fault. I'm not sure on this and would appreciate another opinion??

Thanks
Tim.

 

its been my experience that the ABS light comes on before the charge light.

what is the voltage at the alternator? if that is in spec, you have a bad/dirty connection.

if its low, replace alternator and recheck

 

I would put a meter on the battery terminals and also see what voltage the alternator itself is putting out.

Rule that out before going farther.

Many times, though, if the ABS light isn't off sitting in the driveway but comes on when you start driving it's a wheel speed sensor. They can be a bitch to properly check since the connectors for the rear sensors are under the storage bins and the front sensors are buried in the engine bay. May be able to test resistance at the connector to the ABS computer, though.

Dale

 

Thanks for the replies to this. Have fully checked all wheel speed sensors both at their connectors and back at the ABS computer. All in good order. Terminals B and S of the alternator are also within spec. The only discrepancy seems to be the output at terminal L of the alternator which is reading 11.5V instead of 12.9 - 13.5. ( when measured at both the alternator and at terminal AC of the ABS computer) Not sure if there is anything on the car that can be causing this or if it is down to a fault with the alternator.




Tim.

 

replace alternator and recheck

 

Appreciate that j9fd3s. Was looking to verify what was at fault before firing £250 into a new alternator...

 

Struggling for ideas now, felt sure this was an alternator issue so despite alternator specialist saying all was fine, I replaced the rectifier and regulator. Exactly the same issues. Dimly lit charge light with ignition on and terminal L voltage at idle of 11.5V instead of 12.5+V. With ignition on terminal L reads c6V instead of the 1V specified in FSM. Figure this is something on the car now but not really sure where to start looking, any ideas would be appreciated...

Tim.

 

Is the alternator painted or powder coated? Seen weird stuff when the alternator doesn't ground itself to the block through the frame of the alternator.

Dale

 

Hello Dale.

No its all as standard. Have checked for a decent ground, all ok.

Tim