Another speedo thread - Yes I've read all the old ones!

[yorkshire480]

Well it's been a fun couple of weeks.

Speedo stopped working and unlike previous failures I've been unable to get it to start working again by jiggling the wires/reseating the connector block.
Totally dead, no movement when playing with the wires as before.

I've scoured the numerous topics on here and this is what I've done thus far. I hoping you'll be a able to tell me what I've missed.

1: Removed battery/air box and measured the resistance at the sensor connector. It was 3.2 ohms from memory (Should have written that down!)
Checked the resistance at the connector block where the sensor coaxial cable black and green joins. It read slightly higher which makes sense.

Conclusion: The sensor's working

2: Disassembled the info cluster. Found some dry joints - refreshed them, cleaned PCB, put it back together. Mine has had the volvo repair of soldering the pins so I made sure they're making contact.

Put it back in the car....nothing. No speedo or info relating to it. IC went a bit weird for a while but returned to normal.

Solution: Bought a 'known working info center'. Put it the car - same result. No speedo.

My only thoughts now are that grey connector block is somehow the cause. It's getting a bit ropey. Click over lid has come off and you have to be very careful
not to put stress on the wires.
My only thoughts against this theory is that it would be intermittent or they'd be the odd twitch of the speedo needle but there's zilch.

Your thoughts ladies and gentlemen please....

Happy Xmas too!

[Van]

All I can share now is my sympathy.

[Van]

In the end, on my car it was the speed sensor. On my instrument panel, replacing the computer did not help. My experience is, not all computers work with all instrument panels. I've have two computers from gray/green instrument panels, and they both don't work on my current gray/green instrument panel.
I wonder if my problem ever has been in the instrument panel really.
So, before you mess up the instrument panel totally, replace the sensor. I know it's costing money and it's an awful lot of work. But I honestly wish I had done that first.
If after replacing the speed sensor the instrument panel still does not work, at least you know it's not the speed sensor.

[yorkshire480]

To be honest I was hoping it was the sensor as it's a relatively easy fix. Particularly if you pay someone else to replace it!
All the indications are that it's working though although I think I'll go and double check the expected resistance range.

My replacement info center is different despite having the same plugs and lacks the SRS lights mine has suggesting an earlier unit. Having said all that it behaved identically to mine when in situ. i.e everything worked other than the speedo related stuff.

[glasgowjim]

Changing speedo sensors is not difficult a small mirror and an allen key and the job is done , if you have a turbo then yes it will be awkward but this time you put the car up on ramps or jack up and secure with axle stands and go at it from underneath. With a turbo you can be lucky and get it done in under 20 minutes but it could take you over an hour of fiddling about to get it located. The NA car can be got at from the top and the first time I did it it took exactly 45 minutes after that it takes me about 20 to 30 minutes to remove and refit a new one.

well worth the effort.

Volvo have stuck the prices of replacement sensors sky high damn near doubling so a quest for a workig 2nd hand spare is well worth the effort.

[yorkshire480]

Thanks Jim.

Well I'm slightly confused here as despite the sensor reading within the expected range when measured the recommendation is to replace it?

I'm guessing because there's not much else left to try!

I recently replaced the starter motor so I'm reasonably familiar with down there and reckon I can get the sensor in. I had been wondering whether something had been disturbed when replacing the starter that had effected the sensor and/or cable. Having said that it worked for at least a month afterwards so it seems unlikely.

I'll start the search for a sensor I guess!

Cheers everyone.

[volvo ov lov]

Just a quick point on removing speed sensors - how much comes out when you remove it?

[URL=http://s1328.photobucket.com/user/ ... .jpg[/img][/url]

Should it be the all of the black plastic down to the diff flywheel housing (arrowed in blue) or the bit at the join when the retaining clip rests(arrowed in black)?

My car won't spark so I want to check it's clean. I prised it gentIy and it started to move out at the line indicated by the black arrow started to come out but then got stiff again (oo, er) I don't want to break anything so would like to check before I pull any harder.