Srs light on

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lynx45

Active Member
Posts
101
hi hope someone can help I've got the srs light permantly on in my 02 plate td5 I've gone back to basics and plugged my hawkeye in read DTC came back with code B1018 ( short circuit to ignition in RH pretensioner circuit permanant ) I've tryed clearing DTC but light still on is it just a case of replacing the RH pretensioner or am I looking else where i.e. LH pretensioner, rotary coupler or the airbag plug behind glove box thanks
 
So why not believe what your Hawkeye states, trace the wiring and find where the short circuit is, also test pretensioner as that maybe faulty if so replace it.
Hi I believe what hawkeye is saying just thought I could replace pretensioner or both for a simple fix I'm not that clued up on tracing wiring thanks
 
Check YouTube for many videos on how to ohm out your pretensioner the correct way.
Or follow the link I posted on D2BC for your same question. :cool:
 
Check YouTube for many videos on how to ohm out your pretensioner the correct way.
Or follow the link I posted on D2BC for your same question. :cool:
Thanks will take a look though I'm not confident with wiring / soldering
 
Check YouTube for many videos on how to ohm out your pretensioner the correct way.
Or follow the link I posted on D2BC for your same question. :cool:
Thanks had a look at your link on D2BC did you solder the resistor straight to the 2x wires (orange/red) or could you solder 2x wires to the resistor and scotch lock to the yellow harness making the link also leaving pretensioner unplugged
 
Thanks fery I've just read the link in D2BC this issue is doing my head in as I'm not electrical minded I'm more fit and forget just trying to find with help the easy options within my ability
The SRS light on is a common problem on D2s, it happens on mine all the time. It is usually simply the plug under the driver's seat. The connection is awful, gets dirty, or simply the wire breaks away from it. Many people bypass the connector completely and either use a choc block or even solder the two halves of each wire together. Could it not be possible that the wire has broken away from the connector and is resting on the other connector, causing the short? Check the easy physical stuff first before going to the more difficult stuff and I know what you mean about electrics. I am old school and although I could completely rewire a car from the seventies or eighties, modern electronics kill me!
 
I copy/paste my reply from the other forum just to make clear what's going on in this particular case which has nothing to do with the pretensioner's plug under the driver's seat:

"Hi, unfortunately the SRS ECU is not the best when it comes to generate fault codes cos it can hit and miss from time to time but presuming the code is real cos hawkeye is the most reliable with it the probem is somewhere in the harness which connects to the ECU cos there is no other place where the pretensioner's circuit can meet an ignition live.... to double check the code you'll have to disconnect the battery, unplug the ECU and the RH pretensioner and make continuity test in the ECU plug(C0256) cos if the fault is matching the code you'll have to find continuity across pin 15(ignition live/green wire) and one of pins 6(brown) or 7(brown/red) cos these are the pretensioner's circuit. If no continuity the ECU is suspect and must be ruled out by swapping it, we'll speak again according to the result."
CONCENTRATE TO NOT MEASURE IN OTHER PINS

C0256.jpg

In addition i cropped and edited the relevant part from the diagram to explain cos for that B1018 ( short circuit to ignition in RH pretensioner circuit permanent ) fault code there is a short between the green ignition live and one of the pretensioner circuit's wires which can happen only in the part of the harness where those wires are close to each other or withn the ECU, the pretensioner's yellow plug is C0254 which has no live in it and is far beyond the point where those wires can meet

SRS short to live.jpg
 
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I copy/paste my reply from the other forum just to make clear what's going on in this particular case which has nothing to do with the pretensioner's plug under the driver's seat:

"Hi, unfortunately the SRS ECU is not the best when it comes to generate fault codes cos it can hit and miss from time to time but presuming the code is real cos hawkeye is the most reliable with it the probem is somewhere in the harness which connects to the ECU cos there is no other place where the pretensioner's circuit can meet an ignition live.... to double check the code you'll have to disconnect the battery, unplug the ECU and the RH pretensioner and make continuity test in the ECU plug(C0256) cos if the fault is matching the code you'll have to find continuity across pin 15(ignition live/green wire) and one of pins 6(brown) or 7(brown/red) cos these are the pretensioner's circuit. If no continuity the ECU is suspect and must be ruled out by swapping it, we'll speak again according to the result."
CONCENTRATE TO NOT MEASURE IN OTHER PINS

View attachment 180103

In addition i cropped and edited the relevant part from the diagram to explain cos for that B1018 ( short circuit to ignition in RH pretensioner circuit permanent ) fault code there is a short between the green ignition live and one of the pretensioner circuit's wires which can happen only in the part of the harness where those wires are close to each other or withn the ECU, the pretensioner's yellow plug is C0254 which has no live in it and is far beyond the point where those wires can meet

View attachment 180104
Thanks for the info will check it out How easy is it to get to the srs module?
 
the pretensioner's yellow plug is C0254 which has no live in it and is far beyond the point where those wires can meet
So, although there are two wires going through the connector, neither of them is positive? Didn't know that, so if they aren't where is positive connected to the SRS, and what do these two wires do? Cos one/they deffo cause the SRS light to come on in my truck when one/they come disconnected, and the light does go out when I remake the connection. I do appreciate that there is a lot more than just two wires to the complications of the SRS system, just intrigued and trying to increase my knowledge base. Also, would you have any idea why my SRS light comes and goes intermittently? i.e sometimes I switch on and it's not there, but sometimes it is. Never comes on while I'm driving, always just on start up. (You do know how rubbish I am at electrics and I am not trying to hijack this thread, just hope others reading it may widen their knowledge base at the same time.)
 
If you read carefully my post with the diagrams you should understand, i'll be considered rude again but the system's description is complex and if you want to know check RAVE where everything is fully described, in a nutshell: the deployment of the pretensioners + airbags and the circuit's diagnostic works with digital signal sent by the DCU on those two wires. When SRS involvment is necessary the DCU sends the signal on those wires to deploy . The ignition live and all the other circuits are conncted to the DCU through connector C0256 where all the wires are in a short part of loom together then they split toward each side as i. It's normal to not have live in neither of the pretensioner/airbag wires cos then a chaffed wiring with short to ground on the other wire would deploy it just like that and tose are pyrotechnic devices. If a problem occurs at the two pin plug of a pretensioner or airbag the fault code can be only "pretensioner/airbag open(or short) circuit" as it's about two wires nothing else that's why the particular issue in this thread is more complicated.
just a ''flavour"


SRS circuits.jpg
 
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If you read carefully my post with the diagrams you should understand, i'll be considered rude again but the system's description is complex and if you want to know check RAVE where everything is fully described, in a nutshell: the deployment of the pretensioners + airbags and the circuit's diagnostic works with digital signal sent by the DCU on those two wires. When SRS involvment is necessary the DCU sends the signal on those wires to deploy . The ignition live and all the other circuits are conncted to the DCU through connector C0256 where all the wires are in a short part of loom together then they split toward each side as i. It's normal to not have live in neither of the pretensioner/airbag wires cos then a chaffed wiring with short to ground on the other wire would deploy it just like that and tose are pyrotechnic devices. If a problem occurs at the two pin plug of a pretensioner or airbag the fault code can be only "pretensioner/airbag open(or short) circuit" as it's about two wires nothing else that's why the particular issue in this thread is more complicated.
just a ''flavour"


View attachment 180257
Hi how can knowledge and information be deemed rude that's what these forums are about if anything helps people's issues that's a bonus on the plus side thanks for sharing your information
 
Sieraferry, a typically helpful reply, for which I am most grateful. I know I was being a bit cheeky asking my question as it was not my thread to begin with and your answer gave me all I needed to know. The explanation of what chafing could lead to makes really good sense. Your "flavour" of the wiring concerned with the SRS stuff, was quite enough to be going on with and gives me a starting point to look at if I need to. If I really cannot solve the problem with the help of Rave and my Haynes manual, I will start my own thread. You are not being rude. There are quite a few lazy people who get onto this site and then expect everything on a plate, even some who expect members to post solutions or suggestions to help with their problems which they then pass on to supposedly trained mechanics in their employ! Which to my mind is utter abuse of the forum. So, thanks again.
 
I copy/paste my reply from the other forum just to make clear what's going on in this particular case which has nothing to do with the pretensioner's plug under the driver's seat:

"Hi, unfortunately the SRS ECU is not the best when it comes to generate fault codes cos it can hit and miss from time to time but presuming the code is real cos hawkeye is the most reliable with it the probem is somewhere in the harness which connects to the ECU cos there is no other place where the pretensioner's circuit can meet an ignition live.... to double check the code you'll have to disconnect the battery, unplug the ECU and the RH pretensioner and make continuity test in the ECU plug(C0256) cos if the fault is matching the code you'll have to find continuity across pin 15(ignition live/green wire) and one of pins 6(brown) or 7(brown/red) cos these are the pretensioner's circuit. If no continuity the ECU is suspect and must be ruled out by swapping it, we'll speak again according to the result."
CONCENTRATE TO NOT MEASURE IN OTHER PINS

View attachment 180103

In addition i cropped and edited the relevant part from the diagram to explain cos for that B1018 ( short circuit to ignition in RH pretensioner circuit permanent ) fault code there is a short between the green ignition live and one of the pretensioner circuit's wires which can happen only in the part of the harness where those wires are close to each other or withn the ECU, the pretensioner's yellow plug is C0254 which has no live in it and is far beyond the point where those wires can meet

View attachment 180104
Hi fery just a quick request as my disco is away at moment having welding I understand about chasing /checking the wires but if the srs ecu is faulty is it a case of getting a secondhand one and plugging in or do they need coding? Thanks
 
Hi fery just a quick request as my disco is away at moment having welding I understand about chasing /checking the wires but if the srs ecu is faulty is it a case of getting a secondhand one and plugging in or do they need coding? Thanks
The SRS ECU is plug and play just remember to not work on any SRS element without disconnecting the battery first
 
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