Intermittent Speedometer Failure

[squeasel]

Greetings All! I am looking for advice on the next item to check.

First, the speedometer fails and DSC, ABS and Brake warning lights are solid yellow. This is an intermittent issue that seems not to happen in the morning but does happen in the afternoon. The car is a 2003 3.0L LHD. I found no fault codes though I have just a run of the mill OBDII scanner.

I thought that the left rear wheel speed sensor might be causing trouble so I swapped rear sensors with no change to the symptoms (note: it is my understanding that the speedo is given data by the left rear sensor).

Oddly, when the speedometer is not working, the cruise control will continue to function.

Any advice on what to check next?

Thanks in advance.

[TerminatorX5]

since you have swapped the sensors with no change, than consider a repair of the ABS module - there are companies on ebay selling repair services for under $100 with lifetime warranty. well worth it....

[squeasel]

HI Tx5 ... thanks for the suggestion. I'll look into repair and a new module. Do you know if there is a way to test the current module?

[TerminatorX5]

you can "interrogate" the modules, ABS including for errors using GT1 or INPA... not sure how to bench-test them - what probably is happening, the cold-soldered joint points have come loose, giving you the grief... the repair facilities fix that...

what you can test, is the diodes in the hall-effect sensors - right there at the plug at the wheelwell you put the tester and test the diode... if the sensors are good, then test the line from the wheelwells to the ABS - hint: to skip the line testing, do the test right at the ABS plug - if the diodes are good, you have good sensor and good line... if the reading is bad, then you go deeper...

if the lines, diodes are good, it leaves you with the module... you can repair it yourself but it is a serious PITA - easier to pay somebody to do it for you... and testing of the module - i would leave it to professionals (not the dealers!!!)

[squeasel]

Tx5 ... much thanks. I had started to test the sensors when I discovered my probes didn't fit inside the connector, but since the wheels were off I just swapped the sensors. Since my test procedure seems viable I will go back to that if I can get it to fail at a convenient time. And I'll research the module to see how to do a single test. Much thanks. I'll post results.

[upallnight]

Maybe not a sensor issue but a wiring issue. Perhaps the wiring on the left rear sensor is broken or the connector is bad.

[squeasel]

Hi upallnight ... I had swapped the rear sensors with no change in symptoms, but otherwise it could be a wiring issue in the harness. Unfortunately, it seems to fail by the time the car gets home in the evening and I am not excited about working on it LOL.