1997 850, T-5, auto, IPD sways,IPD ss brk lines, Bilsteins

Four volvos · Post by **Four volvos** » 26 Mar 2007, 23:28

Hello All,
My folks have my former daily driver, 97, 850 T-5. I do all of the maint. and mods. It is strong and fast but...

The speedometer and odometer have failed together. No OBDII codes set, no problems with engine or transmission performance. The wiring diagram in my Chilton shows a vehicle speed sensor connected to the Motronic 4.3 control module. Does this send the impulses to the speedo? How can I troubleshoot this sensor? The Chilton does not mention this sensor in the troubleshooting section.

I know about the plastic gear fix for the odometer, but it does not mention a failed speedometer at the same time. Both worked fine and then failed together.

I do take care of four but only drive the S60R.

Thanks,
4 Volvos
87, 740GLE 200Kmi; 97,850 T-5 125Kmi; 01 XC70 100Kmi; 05, S60R 30Kmi

Post by **Ozark Lee** » 27 Mar 2007, 07:04

The Vehicle Speed Sensor sends a signal to a whole bunch of places including the Engine Control Unit, the Transmission Control Unit, the ABS Module, the Cruise Control Module, the Electronic Climate Control, and the Radio.

What is interesting is the lack of other symptoms in your description of the problem. If the VSS was truly bad the car would, at a minimum, be making some very bad shift decisions. An interesting test would be to get the car up to highway speeds and set the cruise control and see if it works. If it does it would essentially rule out the VSS and point toward either a bad instrument panel or a wiring problem to the instrument panel.

...Lee

Post by **mwy** » 27 Mar 2007, 11:25

I haven't had this problem, but I've seen elsewhere that there is a plastic gear that wears out in the speedo, and fcpgroton has a kit or part for it.

Matt

Four volvos · Post by **Four volvos** » 24 Apr 2007, 12:24

Hello All,
I have more info as I now have the car back. The cruise control does not work, the speedo and the functions for the trip computer that rely on speed info do not work, the electronic trip odo and the mechanical odo do not work. Checked the continuity from the TSS to the speedo connector for both wires, no opens. Resistance across the leads of the TSS is 373 ohms.

I did not check the VSS at all.

This is an intermittent failure. After driving it >20 miles, three separate times, it failed 2 out of the three. No AT problems or engine related issues. No codes were set.

Which of these sensors feeds info for the different functions? Does the TSS give the info for the speedo and the cruise control or is it the VSS? What should the resistance be across the leads for the VSS when it is functional?

I have checked all of the pins in the connector to the instrument cluster and none of them are loose. There are no burnt traces on the instrument cluster PCB.

Is there any info online about these sensors and their functions and operating specs?

Thanks,
Four volvos