[morpheus]

Hi everyone,

Recently I've experienced a strange problem with my taurus 1999 SES. While driving on the highway, the speedometer suddenly fell to zero. Shortly thereafter, all climate controls (vent, A/C...) went dead as well. Everything else works fine. From time to time, the speedometer will come to life again and work perfectly, sometimes for half an hour or more. At other times, the climate control kicks back in.

Whenever the speedometer comes back to life, there is an occasional
effect on the transmission, especially at high speed. In one case, it
caused the car to downshift on the highway, creating a loud grinding
noise.

I'm unsure of where to begin. It looks like an electrical problem, since the instruments intermittently work perfectly. Has anyone experienced or heard of a problem like this? I'm thinking maybe a short in the TRS?

Thanks a lot!

 

[shoz123]

Probably the VSS if the speedo is dropping out.

 

[morpheus]

I thought of the VSS, but the problems seem to be related. Doing some more tests today, I found that all of the fuses are fine, the fan motor is fine, but the airflow switch is not grounded. No idea where to begin troubleshooting that problem though, any more ideas?

Thanks.

 

[shoz123]

What's the air flow switch?

 

[saerandy]

I'd start with the VSS since that would cause the speedo issue as well as the transmission issue when it kicks back in to life. If the computer has no idea of vehicle speed, it may turn off by default to protect some system or another. VSS replacement is an easy, cheap, and fast fix. I'd start there.

 

[ldheinz]

I have the exact same problem with my 96 LX Duratec. Except that it isn't intermittent anymore. The radio controls are also dead, and the defrost is on high all the time. The "football" is dark, but I found that the rear defroster button works.

The VSS is cheap enough to just swap out to try it, but I hear that it's not easy to replace. I haven't looked yet.