REC and AC lights blinking together at startup. Meaning?

850forum · Post by **850forum** » 09 Sep 2019, 11:26

Had the mechanic replace an ABS sensor in one of the wheels. Since then the ABS light goes on for a few minutes after startup but also the REC and AC lights are blinking in synchrony at startup for a (shorter?) period of time.

Post by **abscate** » 09 Sep 2019, 13:16

You have a fault in your HVAC system that the ECC controller is reporting. You can read these codes with a decent scanner (the ones that cost about$100)

If the ABS light goes out when you start driving thats ok, but the same scanner will tell you why it is on keyup (it should test and then go out in a few seconds) - minutes of ON is not normal

Post by **tryingbe** » 09 Sep 2019, 13:52

You can read the codes on a 95 without any scanner.

https://www.matthewsvolvosite.com/read-codes-volvo-850

Post by **jreed** » 10 Sep 2019, 05:09

There is a little home-built ECC reader that works well if you have a '96 or a '97. I used it last weekend with good results to track down a gummed up driver's damper position sensor circuit. For the pre-OBDII cars, you can read the codes the same way, but from the engine compartment instead of plugging into the OBDII port in the passenger compartment.

Fixing the damper:
https://www.matthewsvolvosite.com/forum ... hp?t=51078

Reading the codes:
https://www.matthewsvolvosite.com/forum ... 25&start=0

850forum · Post by **850forum** » 10 Sep 2019, 06:46

They also recharged the AC. Wonder if its overpressure? Is the first step just to try to clear the codes - sometimes they get stuck don't they?

Post by **abscate** » 10 Sep 2019, 08:45

850forum wrote: ↑10 Sep 2019, 06:46 They also recharged the AC. Wonder if its overpressure? Is the first step just to try to clear the codes - sometimes they get stuck don't they?

Direct free kick awarded for witholding information.

Yeah, when they recharged the AC, they probably vacuumed it out, and then the ECC detected low system pressure and latched a code, which they fixed by charging, but neglected to clear codes.

Definitely clear them, but I would read them first which will confirm the above rampant speculation. Its fun, free , and helps you to come to terms with your Volvo.

850forum · Post by **850forum** » 11 Sep 2019, 01:49

There is a photo of a homemade ECC code reader using an LED here:
https://www.matthewsvolvosite.com/forum ... 25&start=0
But its obscure. IIRC LEDs have to me wired in a particular direction & he did not say if the blue or the red wire is the "direction of electron flow."
Labels are obscured to: Pin 16, ECC and ?? N for Neutral ??

Post by **jreed** » 11 Sep 2019, 05:10

On my '97, the connections are pin 5 (GND), 6 (ECC) and 16 (+12V).
There is a circuit diagram here:
https://www.matthewsvolvosite.com/forum ... 10#p251189
Note that in the diagram the communications connection is shown to pin #3, which is for the Motronic system. For the ECC system, use pin 6 instead of pin 3. The ground connection (#5) and battery voltage connection (#16) remain the same.

850forum · Post by **850forum** » 11 Sep 2019, 17:10

I have a 1995. I'm becoming aware that some electronics changed for 96-98, then again thereafter (for example, ABS).