1999 S70 - SRS light and Heated Seat Issue

Reinie · Post by **Reinie** » 22 Jan 2015, 08:24

My SRS air bag light decided to come on after 198,00 miles of service and the driver side heated seat quit working. Sounds like I have a sensor or wiring issue. I would like to find the fault issue before I attempt a soft reset or pay to get the codes off VIDA. I took a glance under the seat and the wire harnesses are all connected. Anyone had this issue and know where to start troubleshooting?

Post by **Ozark Lee** » 22 Jan 2015, 08:38

Without a scan on the SRS all you can do is guess. There are tons of people with VIDA/DICE out there and perhaps another member in your area can scan it for you and try a reset. An Indie shop likely wouldn't charge you much either if no members in your area volunteer. The dealer will charge you a full hour (about the price of VIDA/DICE), at least mine does.

The biggest problem I have had with seat heaters on the 70 series is the switch. The left and right switches are the same so you can try to swap them left to right and see of the problem follows the switch. On the 850s it is almost always the seat bottom heater mat which is a PITA to fix.

...Lee

Reinie · Post by **Reinie** » 22 Jan 2015, 09:12

Thanks Lee. Just wanted to post some photos of the wiring. Sounds like the green/purple is for SRS. I might try disconnecting, cleaning, and soft starting the ECU. Likely wishful thinking. Do you think the SRS and heated seat issue could be related? They both occurred recently.

Reinie · Post by **Reinie** » 22 Jan 2015, 09:22

To clarify, I will clean the SRS wire harness connection, not the ECU. Also, if the fault is the pressure / weight sensor in the seat, can that be faked out by jumping the wiring?

Post by **Ozark Lee** » 22 Jan 2015, 09:26

Reinie wrote:Thanks Lee. Just wanted to post some photos of the wiring. Sounds like the green/purple is for SRS. I might try disconnecting, cleaning, and soft starting the ECU. Likely wishful thinking. Do you think the SRS and heated seat issue could be related? They both occurred recently.

That is correct for the SRS wiring, no obvious issues jump out at me. I doubt they are related unless the wiring harness to the seat somehow got chopped.

Did you unplug anything under the seat trying to find the heated seat problem? If you unplug anything related to the SRS, even with the key off, while the battery is hooked up it will trigger a SRS error code.

...Lee

Reinie · Post by **Reinie** » 22 Jan 2015, 09:36

No, I have not unplugged anything. Other than first disconnecting the battery and discharging any residual power, is there anything else to look out for while disconnecting the SRS harness?

Post by **Ozark Lee** » 22 Jan 2015, 17:24

On the '99 there really isn't any other necessary precaution. On the older models there is a plastic safety guard that needs to installed but the '99 models went to electronic triggering rather than an inertia based trigger.

...Lee