1995 850 wagon SRS light does not go on

Erik10 · Post by **Erik10** » 09 Jun 2015, 11:29

Hello all,
My name is Erik (Erik 10).
I just bought an 850 from jan 95. It needs some repairs with which I can mostly cope.
For the next problem I can not find any solution. The SRS light does not go on when I switch on the contact. Lamp is OK (new). Any ideas?

Post by **Ozark Lee** » 09 Jun 2015, 13:58

That is an unusual problem, Usually we get posts when it won't turn off.

Since you have a 1995 you should have the OBD-I diagnostic sockets under the hood (I say should but some European models were a year ahead of North America and the North American cars phased the DTC boxes out in 1996).

The DTC system utilizes the boxes marked A and B under the hood just behind the windshield washer filler cap. Plug the flywire into port B-5 and jot down any flash codes that register. To read the codes just press the button next to the LED for about 1 second and then release it. 1-1-1 means there is no error. After you read the codes post them back.

...Lee

Erik10 · Post by **Erik10** » 11 Jun 2015, 03:12

Hello Lee,
Sorry it took me some time to answer.
The code is 1-1-1, so everything should be OK. Maybe the previous owner or his workshop did a reset. The lamp is OK, but does not go on. I took the panel out again and dubblecheced this! If there was something wrong in the lamp circuit it should have given code 127. I do not understand these results!
I hope you have some ideas.
Erik

Erik10 · Post by **Erik10** » 20 Jun 2015, 13:04

Hello all,
I looked for the electrical plan, and did some further investigations. There are 3 wires going to the SRS control light. There is a black wire, going to mass. Controled that, OK. There is blue-red, going to a 12 V connection over the contactkey. OK, 12 V on position 2 and 3
There is a green-brown going to the central unit, that one gives ca. 3,5 V, when the contact is on position 2 and 3. Here possibly it is wrong, on 2 it should give a short signal so that the function of the warning light is checket. Could it be the central unit? Any ideas?

Regards,
Erik 10

Post by **Ozark Lee** » 20 Jun 2015, 15:21

Book spec is for the signal wire from the SRS controller to the instrument cluster to read 8.0 volts when the key is first turned on (10 seconds) and then drop to 1.5 volts thereafter. The SRS light will be illuminated while the line is at 8 volts and turned off at the 1.5 volt level. That voltage range is a large range and I have no idea what the transition voltage between on and off is other than being somewhere in between the specified voltages.

Where are you reading the 3.5 volts, at the SRS controller in the center console or at the instrument cluster? Does that voltage change after the key is in position II after 10 seconds or remain steady?

It could be a short in the wiring between the SRS controller and the instrument cluster or it could just be a bad SRS controller. If you have a factory amp behind the head unit for the stereo that is a known place where wires from the center console can get shorted to the amplifier heat sink. The heat sink has very sharp edges and from the factory the wires were not well protected from the amplifier.

...Lee