Wiring for the voltmeter & turbo gauge in the 740

OldnDecrepit · 2015-01-25T02:44:54+00:00

The turbo gauge is just a vacuum line. So if you run one off a fitting on the manifold or puta tee on a vacuum hose. It will read still. But they aren't tha...

Bob12

Hi, this is my first post on this site which I 'found' via Google. I am based in the UK, and have owned the same non-turbo 745 with a B200F 5 speed manual for the past 25 years since new.

This thread is exactly about what I am trying to do at the moment with my VDO cluster (as per O&D's second pic in his post of 26 Jan above). It seems that O&D you have cracked it as your last pic seems to be a VDO cluster.

I have taken out the voltmeter from a 'spare' Yazaki cluster that was originally fitted to a turbo and have fitted it to the VDO and now have two wires (+ and -) that need to be connected to somewhere on the back of the VDO.

Can you please let me know which two terminals you attached the wires to .... I am guessing that it will be to some of the original or new spade connectors that connect to the blue printed circuit at the points where any of the 4 screws that merely hold the speedo unit in place.

Thanks for any help.

Bob.

OldnDecrepit

Hi Bob & welcome to the site.

I ran the two wires from my gauge to the battery terminals in the engine bay. I couldn't be sure which ones to use at the back of the cluster. Running them all the way to the battery ensures that you are getting a correct reading on the battery's performance.

Bob12

Ahhhhhhhhh ..... thanks very much for that O&D. That's what I was trying to avoid :) It must be possible as you could get them once as an add on accessory from Volvo, and looking at the wiring diagrams it is connected 'in' the cluster, but it's none to clear where unless you spend ages trying to decipher it. I was trying to avoid it, but I guess I shall just have to have a poke with my multimeter on the terminals that I suspect are the right ones. I will let you know how I get on in due course ... but don't hold your breath!,

OldnDecrepit

If you find out please post it here so we can all learn.

Bob12

Hi .... after several months of inaction! Finally got round to doing something about this (after opening up the speedo and checking drive cogs on odo, etc), and working out the power supply on the backboard. It comes via the 4 tag plug/socket below the speedo on the backboard. Terminal 4 is + from ignition switch when on, and terminal 3 is - ground (they are numbered on the plug).

Have checked it on my breaker and just as soon as finally put cluster together again will confirm and post some pics of the simple wiring of a working Yazaki voltmeter in a VDO.

Bob12

Here's are a couple of pics of the wiring of Yazaki voltmeter in the VDO cluster, and another with the engine running. The wiring is self-explanatory, however you could also connect the voltmeter red + to the top speedo fixing screw that has a single Lucar spade terminal (marked V+ above it). It's the same feed as the the lower terminal (marked +). It's quicker to connect the voltmeter wire to the lower + terminal as you don't have to cut the circular Yazaki terminal off the positive red fly-wire. The negative can only fix to the lower speedo fixing screw marked V - .

Bob12

This is difficult!! You may get 1 or 2 ,or pictures!!

Bob12

No its beaten me ... just 1 ... here's the last one ..

OldnDecrepit

Good work, Bob12.

Bob12

Thank O&D. Its look so uneven now ... I am thinking about using the Yazaki turbo gauge as a basic vacuum gauge off the manifold (the internals look just pressure related). The 'new' cluster is made up from about four different ones! Now it's nighttime over here just done a final check and even the dimmer works OK. :)

OldnDecrepit

Yes, I used my turbo gauge as a vacuum gauge by connecting it to a vacuum line from the manifold.

« Previous Page