Hello, my name is Twan and i have a 1983 244 and i'm having some trouble with getting my speedometer to work. the previous owner installed a 5 speed transmission (i don't know the exact gearbox codes) that doesn't have a connection for the odometer cable. so i did some research and decided to buy a rear axle with a speed sensor since my colleague had one lying around and install a speedometer with an electric odometer. And i've hit the point where i just don't understand it anymore. after wiring the 2 wires from the axle and the switched 12v to the odometer it still didn't work. After doing some more research i found out that one of the 2 wires coming from the axle has to be wired to ground first. after looking at the 3 connections on the odometer one says "+", ons says "⏚" and one says "G". At first i thought the G stood for ground but this stands for "gauge" apperantly. (please correct me if i'm wrong). If i'm correct the speedsensor is inductive meaning it creates its own voltage through magnetic fields, so one of the wires is for ground and the other is a signal wire that delivers voltage to the odometer when the car is moving. Now here is where i'm lost, i thought it was just as simple as wiring the ⏚ connection on the odometer to ground and problem solved but after doing so some smoke appeared in the cluster which was a stupid mistake looking back since i didn't measure what voltage was on this wire, the smoke came from a resistor that is now burned on the motherboard of the odometer. luckily i have a spare odometer so i could give it another go, and this time before wiring anything to ground i went to measure what voltage was on all the wires. on the switched 12v "+" connection there is indeed a 12v when the key is switched to position 2, but on both of the wires from the speedsensor there is give or take a 10v. now neither of these wires are wired to ground since the last time i tried that it went wrong, so i don't know if that has something to with it. But as far as i know when stationary neither of these 2 positions need to read a voltage since one is ground and the other builds voltage when moving, i know all wiring to the odometer is fine since i wired these last week myself, i can't see anything wrong with both of the odometer's as far as the motherboard and the little plastic tooth gears go and i'm pretty confident the speedsensor is fine since it reads an ac voltage when moving.

any information will be appreciated and please correct me if anything i said is incorrect.

 

This link here has good information on the functioning of the electronic speedometer of the Volvo 240

Electronic Speedometer Notes

 

Wow - I understand what you are trying to do. That is put an electronic speedo in a 1983 that originally came with a mechanical speedo, because the transmission currently in the car does not have a connection for a speedo cable (meaning it came out of a 1986+ car)
You are pretty brave to try to figure out how to use a 1986+ cluster in a 1983.

If it were me I'd by a cheap used Garmin GPS - and use that as a speedometer (if knowing your speed was your goal.)