I am trying to decode and understand how the various warning and status light indications (ABS, PSD, Hi-Beam indication etc) are triggered. Are they triggered by being pulled to ground, or by receiving a +12V signal?

I have collected the plug and pin information from the WSM electrical sheets for the 90GT, which should be very similar for the rest of the digital clusters. If anyone knows how these are triggered I would greatly appreciate some information. Please educate me

Cheers!
Carl

 

Most sensors are grounded and go OC for activation (internal pull-up in panel) - this way a break in the circuit = a warning.

However it varies - High beam is just the high beam supply (active high) - what are you trying to do?

Alan

 

Hi Alan,

I'm trying to lay out the wiring to interface with the ISIS electrical system, and since this car will have no stock CEB or factory wiring left, apart from the instrument cluster wiring and ABS, I need to figure out which indicator lights are grounded (parking brake as one example if I understand it correctly), but I am not sure about the turn signal indicator, hi-beam indicator, Check Engine, ABS (thought that was a +12V from ABS computer?) and so on. It seems all sensors share a common ground but was hoping to be able to put a "+" or "-" next to each item listed in the spreadsheet to have it as a reference.

Cheers!
Carl

 

As a follow-up, while the cluster is hooked up to a bench power supply, is it possible to test each connection by either grounding it, or applying +12V to the respective indicator light wire? Would I damage something if I do this? What would be the best way to test it?

Carl

 

I believe you can do that.

Power all (30) & (15) pins - so plug 2: pins 12-13 & 16-17, Plug 4: pin 1

Ground all (31) pins - so plug 2 pins 14-15

Panel should boot up.

You will need to apply 12v to (61) Plug 4 pin 13 to terminate the bulb test.

With nothing connected many of the warnings will illuminate.

Test every switch/monitor input with a voltmeter - they should be in the default active state (high or low) if the lamp is already illuminated. If the associated lamp is not already illuminated they should be in the default inactive state (high or low). Make appropriate notes - then start testing by connecting the inputs as required to illuminate & validate the presumed activation mode.

Some inputs are for analog values from sensors not switches - you can determine most of these, and the above tests are not meaningful there, some of these inputs expect pulsed inputs (speedo, Diag L/K, RX/TX)

Alan

 

Awesome Alan, thanks!

Do you know which plug/pin takes the instrument lights from the dimmer? I noticed there are 3 pins on different plugs that are marked "Terminal 58 Instrument lights". Would you by chance know what the difference is for each? In my setup I would only need dimmable instrument lights, i.e no "daylight bright", but always in a "dimmer mode". Possible?

Carl

 

I believe one is a mistake:

Plug 1 Pin 4 is the supply to the gear selector/reverse switch, as near as I can tell itis unrelated to markerl lights - ignore it - its an output.

Plug 1: pin 2 is the undimmed instrument lights - this switches between the pod illumination modes - when it is low you get high brightness (daylight mode*), when is is high (marker lights on) you get the variable illumination from the dimmer.

Plug 4: pin 14 this is the variable illumination from the dimmer.

*Daylight mode actually varies the brightness itself based on the light sensor at the top of the panel. In low light the instruments will dim, in high light conditions the brightness will be full on.

You can't have always in dimmer mode - because the dimmer itself is only active when the marker lights are on... You could have a seperate dimmer for the pod that was always on - but you can't combine it with the other console clock illumination unless you want those on all the time too.

This stock system is rather good - well thought out and a lot more complex than most folks know of - it just works well, I'd keep it that way, quite easy to do.

Alan

 

Thank you Alan, your input is very much appreciated!

Carl