SRS Light

kippster41493 · Post by **kippster41493** » 01 May 2016, 12:23

I have a 94 850 Turbo. SRS light came on today, wondering what are some common causes for this to happen.

Post by **erikv11** » 01 May 2016, 12:36

oops wrong thread ...

kippster41493 · Post by **kippster41493** » 01 May 2016, 16:25

erikv11 wrote:oops wrong thread ...

why is this the wrong thread? Isn't this for help, advice, and DIY tutorials about 92-00 850's?

Post by **erikv11** » 01 May 2016, 16:41

No, sorry!

I meant, I mistakenly posted a reply here but I put it in the wrong thread. So I deleted the text, but I couldn't delete the post altogether.

On a 94, ABS light is usually a problem with the detection at the wheels. So in order maybe, the suspects would be
- dirty reluctor rings (the things on the axle with the teeth)
- unplugged sensor or damaged sensor wire
- bad or damaged sensor
- slim chance it is the module but these don't usually fail in the 95 and earlier cars.

On a 96+ you can check out the sensors with an ohmmeter, there should be about 1100 ohms each, see troubleshooting at https://www.midwest-abs.com/. Presumably t is the same in your 94 but since the modules are different pre-96, I am not sure.

Post by **polskamafia mjl** » 01 May 2016, 16:56

SRS light is for the airbags. Only the dealer can reset that light.

Post by **erikv11** » 01 May 2016, 22:03

Double screw-up on my part. What he said, not what I said.

Random SRS light may come from the airbag connector under the dash coming unhooked, or something similar in the seats. A simple reset may take care of it but ore likely a wire or connector is amiss.

stevegs · Post by **stevegs** » 17 Mar 2018, 11:06

polskamafia mjl wrote: ↑01 May 2016, 16:56 SRS light is for the airbags. Only the dealer can reset that light.

Yes - if you want to get ripped off! More often then not, a poor or intermittent connection causes it - and just like all the other ECUs in the car, you can read the fault code(s) by plugging the test lead into socket B5 and pressing the test button for 1 second. The codes appear in 3 bursts of flashes of the test LED: if the first burst has 2 flashes, it's a connection problem (or less likely an airbag problem). The second group is the airbag or seatbelt tensioner concerned: 1 is the steering wheel airbag, 2 is the passenger airbag (not always present), 3 is the left seatbelt tensioner and 4 is the right.

The third group is the type of fault: 1 is short circuit, 2 is open, 3 is short to ground and 4 is short to supply. I had 2-3-2 ie. an open circuit of the left seatbelt tensioner, occurring occasionally - more so during hot weather, which initially made me think it was the tensioner fuse going high resistance when hot. The is a note in the service history when the car was 3 years old by a Volvo agent who charged a previous owner £17 just to reset the code without offering a reason why it had set in the first place. It came to a head when the damned light came on during an MoT (in February), which is a failure in the UK. So, time to see what really was going on...

There is a big multiway connector situated behind and below the glovebox on RHD models (not sure about LHD) - finding it is a bit of a pain because the whole glovebox needs to come out, and it's also advisable to remove the cover above the passenger footwell. Sections of the wiring harness are bunched together with sticky tape which, over time, gets VERY sticky. Remove it all - it serves no purpose other than to make finding things unpleasant. One part of the connector has a bar at one end and the other part has a hook. The two parts are supposed to be clamped shut at the other end by a couple of barbs - which weren't engaged in my car. As luck would have it, the SRS leads (with an overall orange sheath) were at the open end - hence the intermittency.... There's no reason why this area should ever have been disturbed during the life of the car - certainly no evidence of this, so it just proves they also have Friday afternoons in Sweden! Clipping the connector together properly solved the problem.

Now to reset the code: as with all the other ECUs, hold the test button down for at least 5 seconds (LED on), release it (LED off) and, as soon as the LED comes back on, hold the button down for another 5 seconds and release it. Press the button again and verify you get the all-clear code of 1-1-1. If not, and you get another code there is another fault. If you get the same code, you didn't fix the first fault.

There are dire warnings not to test airbag fuse resistance with a multimeter - one Honda website says its OK if the meter can only produce 10mA or less - but I wasn't prepared to risk it even though my best meter only produces 0.3mA. The only safe way to isolate a fault to the wiring or airbag is to disconnect the latter and put a dummy 2.2 ohm resistor in its place. Any old 2.2 ohm resistor will do provided its leads are 0.8mm in diameter - and are CLEAN - just insert them carefully into the flying socket. If the fault recurs with the resistor in place, it is with the wiring, not the airbag.

Two other fault codes could appear: 1-1-2 means the crash sensor box (located beneath the centre console between the gear lever and handbrake) is faulty - that probably means a new box is required. The other (1-2-7) means the SRS lamp is open or short circuit.