RWD - speedometer inop

Volvo RWD 900 Forum

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speedometer inop 900 1993

Dear Dom's940,

Hope you're well. To ease removal of the wiring connector from the speedo sensor mounted in the differential cover, apply lots of PB Blaster or other penetrating oil. The oil, given time, will weaken the corrosion bond between the wiring harness connector's metal sleeves, and the sensor's metal pins.

Once the oil has had time to work, cut any remaining wires. The sensor's connector can then be turned, so it points down-ward (towards the ground). That will ease further work.

You may then be able to pull the wiring harness connector free from the sensor by GENTLY tugging on the wiring harness connector's housing. I emphasize gently, as replacing the sensor itself (Volvo #1398321) will cost about $180 at a U.S.-based Volvo dealer.

If the wiring harness connector won't budge - as is likely - use a pliers carefully to break the wiring harness connector's housing, to expose the wiring harness connector's sleeves. Use a needle-nosed pliers to try to turn the sleeves, and so to separate them from the sensor's pins. Do not damage the sensor's wiring connector housing!

Once the sleeves have been removed, clean the sensor's round pins using fine sandpaper and coat the pins with di-electric grease. Then, side onto the wiring harness short lengths of heat-shrink tubing. These lengths should suffice to cover each splice in the wires.

Then splice onto the wiring harness, a compatible two-wire connector. I'd solder the twisted-together wires using a rosin-core solder. Once the wires have been soldered, slide the heat shrink tubing over the soldered joints and shrink the turbing using a hair-dryer of an industrial heat gun on "low".

I'd then wrap both spliced wires with butyl rubber tape. Butyl rubber tape - used to waterproof windshields - is very sticky and remains flexible. Most other water-proofing materials harden with time, crack, and so fail. You should be able to get butyl rubber tape at an auto glass supply house.

I'd wrap the wiring harness connector and the top of the sensor housing with butyl rubber tape. Compressing the tape with your fingers will form it into a "boot". This "boot" will keep water from corroding the connectors.

A dollar's worth of butyl rubber tape that encases completely the sensor's wiring connector will help to ensure you do not need to repeat this job anytime soon.

Hope this helps.

Yours faithfully,



New speedometer inop [900][1993]
posted by  Dom's940  on Sat Apr 13 16:28 CST 2019 >

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