Solid state unit in 850 alarm system(OEM), where is it located

theiceman69 · Post by **theiceman69** » 27 Sep 2021, 18:23

I've been having problems with the Klaxon/hooter for the alarm system. When alarm is triggered, indicators flash all round but hooter did not sound! Removed hooter and tried it out of circuit, works fine. Checked the connector at the end of the wiring, 'NO POWER".
Looking at the alarm circuit diagram; obtained from a member(thank you) it seems that the relay that feeds power to the hooter is not working BUT this is located within a Solid State unit, where is this unit located? Can it be fixed or am I looking for a new unit?
Any help/suggestions gratefully received

Post by **scot850** » 27 Sep 2021, 19:57

The usual 2 places are in the rear section of the main fuse box on LHS (LHD car) by wipers. You have to remove the top cover to access. If I recall there is a relay for the system in there. The Volvo one has the function written on it.

The other place would be (LH drive car) above the pedals on the bulkhead.

This may help. Looks like the 850 is under the dash

https://knigaproavto.ru/shemy/en/volvo/ ... agram.html

The little alarm horn is common failure point.

Neil.

theiceman69 · Post by **theiceman69** » 27 Sep 2021, 23:18

Scot850. Many thanks for the advice and link, very handy. i know what the underside of the main fuse board looks like, went fishing there when I had problems with the Cruise Control(without any diagram to help), so this will be extremely helpful, again, Thank you.
Iceman69