2000 V70 interminnemt ETC light, car runs fine!

velora · Post by **velora** » 08 Jan 2012, 23:31

I have a 2000 V70 XC with about 148k miles on it and ETC light comes on and off randomly. The car runs great at all speeds and idles great when cold/hot. Looks like that ETM works fine (yellow stickered) and my Volvo has no performance issues whatsoever. Also it gets good mpg, average 20-22, up to 25 on just freeway trips.
I picked car as a project with a blown head gasket and while fixing it I replaced all components that need attention at that point (PCV, filters, belts, full tune up, vacuum lines, Re-soldered ABS unit,etc). Only one thing that will have to be replaced is a catalytic converter because it threws CEL every 250 or so miles. After some research I found that issue may be related to a MAF sensor or to brake light switch, also somebody mentioned that a new battery got rid of ETM light.
What are possible hints to that stupid light? I cleaned ETM two times already, it does not have any performance issues, it just pops randomly and disables cruise.
Thanks

Post by **jblackburn** » 09 Jan 2012, 00:27

Mass airflow sensor OR a vacuum line can cause this (the cat converter code is a good indicator of a leak or a bad O2 sensor).

IAS-S70 · Post by **IAS-S70** » 09 Jan 2012, 02:22

Try check brake pedal position sensor which located at brake servo. This culprit sensor also caused ETS light comes on and off randomly. I was facing this problem before.

Good luck..

velora · Post by **velora** » 09 Jan 2012, 22:27

New catalytic converter is on order. Also will check brake sensor as well. What is correct resistance for it?

velora · Post by **velora** » 02 Feb 2012, 23:22

Took a car to my buddy who has advanced diagnostic scanner and we got only one code - ECM-9400 (Brake pedal position sensor. Faulty signal) . Seems that this is a reason to actuate ETC light. Now I googled the issue and found that two sensors might be reason - the Brake light switch (part # 9128577) or Brake booster sensor (part # 9441116). How do i know what needs to be replaced? Thanks

Post by **regent** » 03 Feb 2012, 09:30

The code may be a bit tricky to interpret, but I would start with the Brake Light Switch to eliminate it from the equation - see if your brake lights come on as soon as you tap the pedal every time and go out as soon as you take your foot off of it. With a meter, the contact should 'switch state' between 'open' and 'closed' (or read 'next to zero' ohms and 'infinity').

Before condemning a sensor, make sure the electrical connectors look OK (oxidation, recessed pins and in that order)
Please post back if you need diagrams

velora · Post by **velora** » 25 Feb 2012, 20:48

Replaced Brake booster sensor (part # 9441116) and everything is normal now. ETC is off and cruise working! Still weird how those components are interconnected...

Post by **VCA** » 11 Apr 2014, 13:16

velora wrote:Replaced Brake booster sensor (part # 9441116) and everything is normal now. ETC is off and cruise working! Still weird how those components are interconnected...

Another data point: ETS light illuminated on my '99 S70 GLT...same code (ECM-9400, signal too high). Replaced sensor, cruise control came back to life and the gearbox problem I had been having (dropping out of lockup) went away. Apparently this position sensor informs the ETM how much brake is being applied so it can judge how much to close the throttle by and/or give engine braking.

Post by **shiloh51933** » 18 Oct 2016, 15:54

velora wrote:Replaced Brake booster sensor (part # 9441116) and everything is normal now. ETC is off and cruise working! Still weird how those components are interconnected...

Thank you for making this thread, after reading this thread it confirmed what I had believed was going on with my 2000 V70XCse. I have all the same issues, ETS light illuminates without the CEL illuminating, no cruise control, idles fine and runs gd but surges when I give her a gd amount of throttle and the gearbox clunk when locally driving while stepping on brake. I'm ordering the brake booster sensor now.