As title says, my Volvo came up "TRANSMISSION SERVICE REQUIRED" and is throwing TCM-001F and TCM-0020 error codes:

TCM-0020 Transmission Output Speed Sensor (Faulty signal)
TCM-001F Vehicle Speed Sensor (VSS) (Signal Missing) AW55-50/51SN Transmission

As far as I can tell there are three sensors ...

If I understand you correctly, the car runs fine now. Just to be clear, you can’t troubleshoot this (except visual) until the issue reoccurs.

If your measurement regarding less than 1v in front of car is correct (hopefully, you had a good clean connection with voltmeter), you are almost there ...

I'll make the measurement and snap some pix

It does,t matter if the small lights on as long as they are on for both measurements.

Captions to follow. Ambient temp 1.0 C


Legend, thank you so much! It's an ambient temp here of 29 C and after midnight, so i'll give this a shot first thing in the ...

You just look at The voltage to ground across the battery, and the voltage at the fuse box to a good ground on the engine. No need for long cables.

If you are worried about the ground cable, remove it and measure resistance on it directly. You can use a temperature gun to see if it gets warmer ...

Test the battery. If you have a few bad plates in it, it can still give you 13 volts but once you demand some amps, it 'croaks'.


Battery is new as of 2 weeks ago, and i'd had it on a 6A charger before the no-start issue happened (reading 13.2V at the battery). Starts fine now, but i'm still not ...

oragex wrote: 30 Nov 2018, 09:12 Do you have light at the car plate? In no, undo the trunk door cover and disconnect the cable to the trunk switch and plate light (use the key to open the trunk first, see if it works to open it)

Huh interesting. What's the rational behind this one? Would a blown light cause a battery drain?

I don’t, but I might be able to rig up something... failing that, and if they pass a visual inspection, any ideas on where else to look?

Ends of the cables look clean as a whistle. It never stops below 60F here and there’s no salt corrosion. Any way of testing this with a multimeter?

past 4 months have been a nightmare with the Volvo, looking for a bit of help diagnosing the problem(s).

Back in August I was getting low voltage problems and needed to jump start the Volvo despite constant driving. I ended up losing power queued in traffic on a main road (nightmare). Ended up ...

Replying to my own post here - ended up taking it to a Volvo mechanic cross-town who was able to remove the filler hose and nec and replace the rubber connector ([#19] on the above diagram). Just in case anyone else runs into this issue - it can be remove and replaced without dropping the fuel tank ...