SRS Light

Fred Byrne · 1st August 2020, 12:20

I was tidying the car and removed some cottonwool wadding that the previous owner had put under the left front seat. The SRS light came on afterwards. I put the wadding back and the light went out but after a few miles it lit again. I removed the front seat securing bolts and tipped the seat back so that I could get at the plugs. I wiggled and waggled the plugs . Cleaned them with switch cleaner but no joy. I then removed the yellow plug and soldered the wires. Still no joy.TOAF gives the following readings.

9134- Side Sensor; communication error
9035- Ignition Circuit IC4 sidebag front seat left resistance low
9132- Side sensor left plausibility error
9036 Ignition circuit IC4 sidebag front seat resistance high
9015 ignition circuit seat pretension left resistance too low

The only plugs I touched were the yellow and blue ones and I replaced the yellow plug with soldered joints. Can there be a polarity issue in the case of the yellow plug soldered connection? but both leads have the same colour coding.
Does the fact that the seat is tilted backwards at about 45 degrees matter? Or does the system require time to reset the codes? Hope some kind person can enlighten me please

Fred

vitesse · 1st August 2020, 12:51

Isn't the side sensor the under the carpet one?

Regards

Fred Byrne · 1st August 2020, 13:39

I think that is correct but I cannot understand why this sensor should fail in co-incidence with for example the seat belt tensioner. I' ll disconnect the sensor plugs and clean them but I'm not hopeful. Many thanks for your reply.

Fred

ADO282 · 1st August 2020, 16:49

I seem to recall the sensors on the early cars fail after being wet for prolonged periods.

When I removed the carpets from my car, although the carpets appeared to be dry, the foam stuff was sodden underneath.

The water had been coming in from around the big tube thing under the rear seat, which had a rusted hole in it.

When the garage read the fault codes on my car, the only thing coming up was the seatbelt tensioner circuit, which was due to a corroded connector, which has been replaced, so I consider myself to have dodged a bullet in that respect.

I'm sure some of the more experienced hands will come up with a detailed explanation for you.

Chris.

Fred Byrne · 2nd August 2020, 16:45

I am now down to two interconnected errors, namely;
Side sensorcommunication failure
side sensor plausibility error

I don't know what a plausibility error is. Anybody know? Anyway sometime soon I'll get round to this problem again. MOT always appears on the horizon very suddenly and unexpectedly so must not delay too long
Fred

Mike Noc · 2nd August 2020, 18:22

A plausibility error is when the ECU's detect a response that isn't what is expected, but there isn't a known error condition to put it down to. For example with an ABS sensor, if some magnetic reluctor segments are missing in the wheel bearing when they pass the sensor the ECU will activate the ABS on that wheel at slow speeds because it thinks the wheel is locking up, as that is exactly what the sensor sees, or rather doesn't see, when the wheel actually does lock up. But if it keeps seeing the same wheel locking up when none of the others are then that isn't plausible, so it alarms a plausibility fault.

If you sort the sensor communicaion failure then more than likely the plausibility error will disappear too.

1st August 2020, 12:20	#1
Fred Byrne Avid contributor Rover 75 Saloon Join Date: Jun 2018 Location: Ballynahinch Posts: 194 Thanks: 69 Thanked 60 Times in 23 Posts	SRS Light I was tidying the car and removed some cottonwool wadding that the previous owner had put under the left front seat. The SRS light came on afterwards. I put the wadding back and the light went out but after a few miles it lit again. I removed the front seat securing bolts and tipped the seat back so that I could get at the plugs. I wiggled and waggled the plugs . Cleaned them with switch cleaner but no joy. I then removed the yellow plug and soldered the wires. Still no joy.TOAF gives the following readings. 9134- Side Sensor; communication error 9035- Ignition Circuit IC4 sidebag front seat left resistance low 9132- Side sensor left plausibility error 9036 Ignition circuit IC4 sidebag front seat resistance high 9015 ignition circuit seat pretension left resistance too low The only plugs I touched were the yellow and blue ones and I replaced the yellow plug with soldered joints. Can there be a polarity issue in the case of the yellow plug soldered connection? but both leads have the same colour coding. Does the fact that the seat is tilted backwards at about 45 degrees matter? Or does the system require time to reset the codes? Hope some kind person can enlighten me please Fred

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1st August 2020, 12:51	#2
vitesse I really should get out more....... Rover 75 Saloon Join Date: Jul 2011 Location: Gävle Posts: 2,528 Thanks: 395 Thanked 823 Times in 652 Posts	Isn't the side sensor the under the carpet one? Regards

1st August 2020, 13:39	#3
Fred Byrne Avid contributor Rover 75 Saloon Join Date: Jun 2018 Location: Ballynahinch Posts: 194 Thanks: 69 Thanked 60 Times in 23 Posts	I think that is correct but I cannot understand why this sensor should fail in co-incidence with for example the seat belt tensioner. I' ll disconnect the sensor plugs and clean them but I'm not hopeful. Many thanks for your reply. Fred

1st August 2020, 16:49	#4
ADO282 Banned ROVER 75 Connoisseur Join Date: Jul 2020 Location: BRACKNELL Posts: 270 Thanks: 125 Thanked 130 Times in 92 Posts	I seem to recall the sensors on the early cars fail after being wet for prolonged periods. When I removed the carpets from my car, although the carpets appeared to be dry, the foam stuff was sodden underneath. The water had been coming in from around the big tube thing under the rear seat, which had a rusted hole in it. When the garage read the fault codes on my car, the only thing coming up was the seatbelt tensioner circuit, which was due to a corroded connector, which has been replaced, so I consider myself to have dodged a bullet in that respect. I'm sure some of the more experienced hands will come up with a detailed explanation for you. Chris.

2nd August 2020, 16:45	#5
Fred Byrne Avid contributor Rover 75 Saloon Join Date: Jun 2018 Location: Ballynahinch Posts: 194 Thanks: 69 Thanked 60 Times in 23 Posts	I am now down to two interconnected errors, namely; Side sensorcommunication failure side sensor plausibility error I don't know what a plausibility error is. Anybody know? Anyway sometime soon I'll get round to this problem again. MOT always appears on the horizon very suddenly and unexpectedly so must not delay too long Fred

2nd August 2020, 18:22	#6
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,547 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	A plausibility error is when the ECU's detect a response that isn't what is expected, but there isn't a known error condition to put it down to. For example with an ABS sensor, if some magnetic reluctor segments are missing in the wheel bearing when they pass the sensor the ECU will activate the ABS on that wheel at slow speeds because it thinks the wheel is locking up, as that is exactly what the sensor sees, or rather doesn't see, when the wheel actually does lock up. But if it keeps seeing the same wheel locking up when none of the others are then that isn't plausible, so it alarms a plausibility fault. If you sort the sensor communicaion failure then more than likely the plausibility error will disappear too.