96 850 Platinum wagon speedo problem.

Post by **scot850** » 05 Jun 2018, 20:03

One of my Volvo friends in Alberta called me today to ask for help. He had just driven over a rural train crossing that had a hidden dip and hit the suspension hard. particularly at the front. Shortly after he started to get intermittent speedo readings and then it dies altogether. No odometer either.

It could be the famous broken speedo gears but then if that was the case why did it not just stop immediately. If it is intermittent first would that suggest it was possibly not that?

Trying to remember, but the 850 does not use the ABS sensors for reading the speed, is that correct? Does it not have a speed sensor on the transmission instead?

Any thoughts what this may be other than that? I did think about a loose dash and maybe the connector on the speedo getting damaged/loosened, but nothing else that he told me is not working.

Thanks,

Neil.

Post by **FLXC90** » 05 Jun 2018, 22:44

You are right, Neil. The pre-96s used a VSS or trans output sensor, and it is mounted on the bottom of the trans IIRC. The wiring could have gotten yanked on a particularly rough area that could protrude above the subframe level. I would find it unlikely, but who knows.

Post by **scot850** » 05 Jun 2018, 23:10

I have gotten more info. Apparently the ABS has been out on this car for a while, so it may well be the ABS module is bad.

From what I can see and from what FLX90 has added the 95 has a speed sensor output signal as well as an incoming signal sensor.

(6 only shows the one sensor below the airbox area. So I am thinking like the later cars they use the ABS for the speed signal for the speedometer which runs through the ABS module.

So that would leave the same problem I had on my 2000 V70 NA which would have the various random lights coming on and off as well as the speedo and odometer dropping in and out. The main differences are the digital read out on the later car and the electro-mechanical version in the earlier 850. Only other issues I can think of are:

1) A bag connector on the ABS harness to the ABS module
2) A wheel sensor or the wire to it got damaged.

Thanks FLX90 for the input. Appreciated.

Neil.

Post by **FLXC90** » 05 Jun 2018, 23:20

Yeah but, oops, I see now that it IS a 96, which would be ABS controlled. (should have re-read the thread title, not just responded to the one block!) Also, on the 850 odo gear, do the speedos die also, or it should just be the odometers that drop out.

Post by **scot850** » 05 Jun 2018, 23:21

That is ok. I realised what you were trying to say!

Thanks,

Neil.