Rav4 T180 Airbag Srs System

April 20, 2008

Hi

As some of you may remember, last year I bought and had repaired an accident damaged Rav4 T180. The Rav4 was repaired to impeccable standard to such an extent that the dealer did not realise that it had even been repaired.

However, I am having some difficulty with the Airbag System. The drivers, drivers knee and passengers airbags along with the Airbag Spiral (in the steering wheel) and the actual Airbag Module itself have all been replaced. However the Airbag light still comes on on the dash. The car has been back into a Toyota dealership who had it for two days without being able to diagnose the fault. The ECU has no record of any faults and so therefore they say that they cannot diagnose the fault. This is also the second time it has been in.

I am getting to the end of my tether with this now and would just like to find the solution. Toyota have said that the only way is for me to spend thousands and have the entire system replaced, including the wiring loom. I think this is daft and there must be a simple answer. After all, these arent complex systems!!

Is there anyone who has any ideas?

Cheers, Simon

April 20, 2008

Hi Simon . Yup, I remember.

Wot you need is a good electrician/Jap car specialist. Dinna waste time oan the T dealers.

If ye were up here in Lanarkshire, I'd recommend the guys who have/are doing/look after my 2 RAVs as both have had 3SGTE engines fitted; and looms replaced and amended. You need someone who knows how to look outside the box. Ye dinna find them in dealers. I found Jap specialists have a better understanding of things, so try googling or buying some Jap car mod garages.

April 20, 2008

Hi Bothwell,

Many thanks for your reply. I really do appreciate it. Thanks for the suggestion of a Auto Electrician, have found one in Hereford so will give them a call tomorrow and get the Rav4 booked in. I just would have thought that the main dealers with all their diagnostic kit etc would be able to figure out why a light is coming on. At the end of the day - these are their cars! If I wrote some software and couldnt fix it, I'd be sacked!!!

Anyways, will let you know how I get on...

Cheers, Simon

April 20, 2008

My comments to you will be in red;

This explains the air bag light diagnosis;

Primary check

Turn the ignition switch off. Wait for at least 2 seconds, then turn the ignition switch on (IG). The SRS warning light comes on for approximately 6 seconds and the SRS airbag system diagnosis (including the seat belt pretensioner) is performed.

HINT:

If any malfunctions are detected during the primary check, the SRS warning light remains on even after the primary check period has elapsed.

Constant check

After the primary check, the center airbag sensor constantly monitors the SRS airbag system for trouble.

HINT:

If any malfunctions are detected during the constant check, the center airbag sensor functions as follows:

The SRS warning light comes on.

The SRS warning light goes off, and then comes on again. This blinking pattern indicates a source voltage drop. The SRS warning light goes off 10 seconds after the source voltage returns to normal.

Review

When the airbag system is normal:

The SRS warning light comes on only during the primary check period (for approximately 6 seconds after the ignition switch is turned on (IG)).

When the airbag system malfunctions:

The SRS warning light blinks after the primary check period has elapsed.

The SRS warning light goes off after the primary check, but comes on again during the constant check.

The SRS warning light remains off even after the ignition switch is turned from off to on (IG). However, if malfunctions such as an open circuit have occurred in the wire harness between the meter and ECU, the warning light comes on 10 seconds after the ignition switch is turned on (IG).

HINT:

The center airbag sensor keeps the SRS warning light on if any malfunctions have been detected in the airbag system.

Does the air bag light follow any of these patterns? It also goes on to highlight the following difficulties (in case no fault is indicated);

HINT:

The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough problem analysis must be carried out. A simulation of the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be carried out. No matter how much skill or experience a technician has, troubleshooting without confirming the problem symptoms will lead to important repairs being overlooked and mistakes or delays.

This leads to a standstill in troubleshooting.

Simulation method: When vibration seems to be the major cause

HINT:

Perform this method only during the primary check period (for approximately 6 seconds after the ignition switch is turned on (IG)).

Use your finger to slightly vibrate the part of the sensor considered to be the problem cause, and check whether the malfunction recurs.

HINT:

Wiggling the relays too strongly may result in open relays.

Gently wiggle the connector.

Slightly shake the wire harness vertically and horizontally.

The connector joint and fulcrum of the vibration are the major areas to be checked thoroughly.

The bottom line is you need to be very specific about how the airbag light shows, I can then give you the explanation from the fault guide.

April 20, 2008

My comments to you will be in red;
This explains the air bag light diagnosis;
Primary check
Turn the ignition switch off. Wait for at least 2 seconds, then turn the ignition switch on (IG). The SRS warning light comes on for approximately 6 seconds and the SRS airbag system diagnosis (including the seat belt pretensioner) is performed.
HINT:
If any malfunctions are detected during the primary check, the SRS warning light remains on even after the primary check period has elapsed.
Constant check
After the primary check, the center airbag sensor constantly monitors the SRS airbag system for trouble.
HINT:
If any malfunctions are detected during the constant check, the center airbag sensor functions as follows:
The SRS warning light comes on.
The SRS warning light goes off, and then comes on again. This blinking pattern indicates a source voltage drop. The SRS warning light goes off 10 seconds after the source voltage returns to normal.
Review
When the airbag system is normal:
The SRS warning light comes on only during the primary check period (for approximately 6 seconds after the ignition switch is turned on (IG)).
When the airbag system malfunctions:
The SRS warning light blinks after the primary check period has elapsed.
The SRS warning light goes off after the primary check, but comes on again during the constant check.
The SRS warning light remains off even after the ignition switch is turned from off to on (IG). However, if malfunctions such as an open circuit have occurred in the wire harness between the meter and ECU, the warning light comes on 10 seconds after the ignition switch is turned on (IG).
HINT:
The center airbag sensor keeps the SRS warning light on if any malfunctions have been detected in the airbag system.
Does the air bag light follow any of these patterns? It also goes on to highlight the following difficulties (in case no fault is indicated);
HINT:
The most difficult case in troubleshooting is when no symptoms occur. In such cases, a thorough problem analysis must be carried out. A simulation of the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be carried out. No matter how much skill or experience a technician has, troubleshooting without confirming the problem symptoms will lead to important repairs being overlooked and mistakes or delays.
This leads to a standstill in troubleshooting.
Simulation method: When vibration seems to be the major cause
HINT:
Perform this method only during the primary check period (for approximately 6 seconds after the ignition switch is turned on (IG)).
Use your finger to slightly vibrate the part of the sensor considered to be the problem cause, and check whether the malfunction recurs.
HINT:
Wiggling the relays too strongly may result in open relays.
Gently wiggle the connector.
Slightly shake the wire harness vertically and horizontally.
The connector joint and fulcrum of the vibration are the major areas to be checked thoroughly.
The bottom line is you need to be very specific about how the airbag light shows, I can then give you the explanation from the fault guide.

Sometimes I wish you'd leave your love life with Flossie out of this forum......it really gets quite physical if not exual.

April 21, 2008

Hi Anchorman,

Many thanks for your lengthly response - it seems that you know an awful lot about these Rav's!

To add some more information...

I have also replaced the seatbelt pretensioners - forgot about those!

The series of events is as follows. When you press the button to start the car (or just switch on the ignition) the small airbag light and exclaimation mark (under the rev counter) will come on. Then a few seconds later (6 sounds about right), when the engine is running (or when the ignition is on), the little display underneath the speedo will come up saying Check Airbag System and a small logo next to the text which replicates the light under the rev counter. Both lights and also the message will then stay on constantly until you switch the car off again.

I have found with a little playing that no combination of turning on the ignition/starting the car will change the way that this happens or prevent it. However, I am open to any suggestions!!

Cheers, Simon

April 21, 2008

Simon

Has this been malfunctioning since the accident?

Were the impact sensors behind the bumper replaced and reconnected?

Are you aware that all of the connectors in the air bag system are special gold plated ones that have individual instructions for connecting and disconnecting? This is because all of the plugs are capable of shorting the circuit for maintenance. It means that you can unplug a component without deployment of the associated bag and maintaining a circuit for the rest of the system. Each connector has a lock device and a sequence for disconnecting - e.g. you slide back a lock after the plug has been placed into "connection" or "half connection" mode then separate the wires. It obviously means that when reconnecting it would be easily possible to reconnect the wire and not re-establish the circuits. In this case the air bag computer would sense a connection and not sense the right resistance of the air bag unit (it would think the part was faulty).

Whenever that airbag light remains on there is definitely an output to the DLC3 and trouble codes that take you to the fault should be readable with an OBDII reader. I recommend you spend the £30 and get one;

http://www.talktomycar.co.uk/products/codereaders/mj004.htm

However, if there is definitely no code then there is a problem with the DLC3 connector under the dash.

There are also some special precautions for working on the system as each of the SRS devices contain back up power devices that hold a charge for at least 90 seconds and are quite capable of deploying the device. In an accident the air bag can save your life by limiting the amount of movement of certain parts of the body but if one should hit you from the wrong direction while you are working on the vehicle you might as well be in an accident without any air bags.

For this reason I strongly recommend you go onto the publications website and read the instructions from the manual. It is very logically laid out starting with an explanation of the system, precautions, checking the system is complete and then the diagnosis procedure. It is far too long and detailed for me to go through here. You can find the manual here and it will cost you about £3 on your credit card;

http://techdoc.toyota-europe.com/

Go to payable access under the repair tab. Somebody pm'd me not long ago because although they paid they couldn't open the manual. If this happens hold the control key down while clicking the link and it will open.

If you want to discuss more beforehand pm me with a land line phone No.

Cheers