about 2 months ago the speed started acting erratic, boucing around for speedo, off-on-off. Then the ABS would start also, on-off-on-off. and check engine light came on. Speed sensor code and abs malfunction (could be speed sensor related). Replaced speed sensor. cleared codes. Then still no speedo and abs on constantly and check engine light on. Read code -Speed sensor only, no ABS code. Put in 2nd speed sensor today, cleared codes. Started it up no speedo and no codes, ABS on. ??????
To do "most logical easiest next thing", I would suggest testing wires between diff sensor and "RABS Data Link" connector. Also easy (but would not cause speedo inactivity) would be to check G108, the black w/white ground wire at left radiator support.
Speedo signal probably runs thru GEM and then to cluster.
I will check conductivity on both leads from the diff sensor this evening as well as the ground wire at the left radiator support. Do you have anything more specific regarding the location of the RABS date link connection other than left rear of engine compartment?? I was going to pull the connector off the RABS module and check conductivity from diff sensor to there but its sounding like I should not break that connection as it may need re-programming if I do (or is that only true if you replace it?)
Thanks for the help!! I hate electrical gremlins!!
OK yesterday after I replaced the speed sensor I drove the car a few miles, no speedo, no error code, ABS light on, no check engine light.
Today I drove the car truck several miles, ABS light on to start. No speedo. after a few miles check engine came on, returned home. P code of 0500 speed sensor malfunction. Only code. Finally found connection G108 behind the battery. Opened that connection, cleaned all the electrical connections to a bright finish, wire was good, no breaks in the insulation. re-installed. Turned key on to clear code (0500 which I did) this time I noticed the ABS light went out after a few seconds, but once the car was started ABS light immediately came ON. Drove the car less than a mile, no speedo.
That's it for this evening I'll check the RABS data link connector tomorrow evening.
I have the flow charts for that code. It's the original service literature and the techniques used are not the best. They only use resistance measurements to test the integrity of the wiring and various connectors. Load testing is much better.