Hi All ,

This is my 1st post .
I have a 1990 928 s4 and in need of the alarm/central locking module location .
The interior lights only work when you manually switch them on , they do not work when the foors are opened .

Thanks

 

That module sits under right hand seat, but it's not responsible for interior light control.

You may have corrosion of both pin switches registering door open condition, preventing them grounding to car body. The lights are on a timer, so another possible culprit is the timer relay. The switches in all the interior lights may have failed - the units are a poor design and don't like heat from original incandescent bulb.

Does hatch release pull switch work work in both doors? If so then the pin switches are ok.

 

Hatch will open from both switches when either door open .
The car has a couple of issues which I would like to repair .
1 : interior lights n/w when door open
2 : speedo rolls right round to 180mph when ignition switched on
3 : coolant warning stays on when engine running
I have managed to locate a wiring diagram for my car which seems correct for my '90 model . Unfortunately it does not show any component location or actual image. Any input will hopefully save me time and effort and not to mention dismantling my pride and joy .

 

In a '90 model you have a dedicated interior light relay on the CE panel. In your model year I believe central locking & alarm functions (separate) are located in the center console & above glove box respectively.

Only in '91 & later models was it integrated into the combined lock/alarm/interior light module.

Alan

 

Thanks Alan - I never realised interior light control integrated with alarm, and I have a 91!

Not had to work on interior lights though, other than to change all to LED with 1/10 of power requirement, but just as much as they stay cool with no risk of plastic buckling.