erratic speedo


elchunk

KCCO
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my speedo has been temperamental for a few weeks now, either working fine or dropping to nothing. so i replaced the existing speed converter that was bodged onto the VSS wiring. now my speedo is working again but it is all over the place? any ideas??
 
Have a look at the plug that goes onto the VSS, the pins in mine had corroded and causing the same problem.
 
^this or double check the connections at the convertor
 
Mine did this. Was due to coolant getting in the plugs for the vss when I had a leaking hose. Changed the sensor and it was okay unless hard acceleration due to the plug still having dried coolant on the plugs connectors and it was hard to scrape off.
 
Mine also did this, corroded pin on the VSS
 
Checked the connections. Looked good. Game them a clean anyway but no difference. Maybe the vss itself could be faulty? Is there any way to check?
 
I should have a spare vss somewhere, we'd need to check the plug type though as some are different iirc.
 
havent had a chance to check anything yet as im only back from holiday. will update when i know more. its a three pin VSS; blue/white, yellow/black and black. i think i wired the converter in correctly as surely it wouldnt read anything if i cocked that up.
 
Realise this may well be sorted by now. If it is, what was it?

You can check the vss but most people won't have the equipment to do it, ie a microcontroller with a pulse in function and some minimal programming would do rightly. You could also use the microcontroller to prove out your speedo and converter using a PWM pin.

It's good practice to check the resistance of the wiring too as any water inside the insulation can cause black wire corrosion, which means the wiring more than likely has to be replaced.

You can give all your connections a clean with a glass fibre pencil too, best thing for cleaning electrical connections.

Also of it's crimped style connections make sure they are tight on the male to female and the crimp on the back of the connectors.
 
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