ECC climate control temp sensor measurements made easier

JordanW · Post by **JordanW** » 30 Jul 2012, 10:41

Matty Moo wrote:That's only up to 1995. He has a 97.

For the ECC, Cruise Control, and even M4.3 on 96 and 97 850's it does in fact work. You actually use the OBDII port under the coin holder. I've used that method to diagnose ECC issues on my 96 850R and on my previous 96 850T.

Post by **Matty Moo** » 30 Jul 2012, 10:50

The vs thread is for the dtc box under the hood, that's what I was referring to.

JordanW · Post by **JordanW** » 30 Jul 2012, 11:17

Ok, this thread from VS, is a little more clear on how to do it. http://volvospeed.com/vs_forum/topic/91 ... 997-850t5/

The DTC's are the same so you can use the listings on VS to decode, or if you have the Haynes manual, or this one on MVS https://www.matthewsvolvosite.com/volvo- ... 96-to-1998

Basically, the ECC and cruise modules were the same in the 850's, in 96 Volvo just took away the under hood DTC connector in favor of the required OBDII in car connector.

Hope that helps and sorry for the confusion.

Post by **jreed** » 30 Jul 2012, 20:14

This is great advice! Thanks!
Based on what I read on VS, I cobbled together a switch, a resistor (5kOhms), a blue LED and some wire to make myself a little "code reader".

: Simple LED code reader for getting ECC codes; LED_resistor_and_Switch_to_read_codes.jpg (60.87 KiB) Viewed 8093 times

I used some iron wire (which seemed like roughly the right diameter to fit snugly but not too tight in the 16 pin OBD-II connector under the coin tray.
The connections are 5 (GND), 6 (ECC) and 16 (+12V). In the diagram below the connection is shown being made to pin #3, which is for the Motronic system. Use 6 for communicating with the ECC system.

: Schematic diagram from VS for the LED "code reader"; LED_code_reader_(use 6 for ECC instead of 3).gif (16.06 KiB) Viewed 8092 times

With the ignition off, I made the connections here. Note that the LED lights up as soon as you plug in the connections, but once you turn the ignition on, the LED turns off.

: Pins 5, 6 and 16 connected to LED reader; Pin_connections_to_read_codes.jpg (64.01 KiB) Viewed 8093 times

: Side view of OBD2 connector showing 5, 6 and 16; Pin_outs_for_OBD2.jpg (52.01 KiB) Viewed 8093 times

This gizmo worked like a charm. I closed the switch for about 1s and then when I opened it there was a pause and then the LED blinked out the first code "2 1 1" ("Driver's side damper motor position sensor open circuit or shorted to 12 V" according to my Haynes manual). I had the fan set to low speed and when the ECC was about to blink back the code it turned off the fan, which was interesting.
After each code I closed the switch again and got
2 3 1 "Ventilation damper motor position sensor open circuit or shorted to 12 V"
2 3 5 "Recirculation damper motor position sensor open circuit or shorted to 12 V"
3 2 5 "Recirculation damper motor active too long"
and then 2 1 1 again.

Amazing! I guess for those who have done this before it's old hat and no big deal. To me, the ability to be able to read out these codes for the first time is very exciting!

Next step is to delete these codes and see which ones if any re-occur. From the Haynes manual it sounds like I have to turn the ignition to On, close the switch for five seconds, open it, wait 3 seconds for the LED to light, and then close the switch for another 5 seconds, and then open it, watch for the LED to go out and then turn off the ignition.

Thanks again JordanW for pointing me in the right direction!

Post by **jreed** » 30 Jul 2012, 20:22

I took a short 30s clip of the codes being blinked back by the ECC system:

[YouTube][/YouTube]

Post by **JimBee** » 01 Aug 2012, 22:28

As I noted, listening to the dampers open and close suggests they are working, but it's hard to know if they are ALL working. i had the blinking lights on my '93 850 when the damper motor was actually working properly but the damper shaft had split causing the cold feet problem.
Glad you found it and thanks for the write-up on your handy code reader!
JimBee

Post by **jreed** » 02 Aug 2012, 08:58

JimBee-- Thanks! You were right about the dampers needing attention. The best I could tell when I tested the air flow a couple of days ago (before I built the little LED code reader) was that the dampers were adjusting the flow of air to the proper positions. The ECC error codes (211, 231 and 235, which I got after building the code reader) suggest that the position feedback sensors inside the damper motors were what was not working correctly. After removing the damper motors and opening them up, there was a lot of white lithium grease residue spread over all the sensor contacts. Once I cleaned that up, the ECC system reset the error codes. All seems to be working well now.

motovovo · Post by **motovovo** » 09 Aug 2012, 21:57

Hi jreed, Is it possible the damper motors are the culprit? Maybe have a look at this.

https://www.matthewsvolvosite.com/forums ... =1&t=27239

Post by **jreed** » 13 Aug 2012, 06:14

Hi Motovovo-- Thanks for the feedback. You called it! It was a damper motor... specifically the feedback sensor inside the damper motor that tells the ECC system the position of the shaft. I removed it and cleaned it up, as described in this post.
https://www.matthewsvolvosite.com/forums ... 5&p=251432

Post by **mecheng** » 28 Oct 2014, 17:21

Are you sure you used a 5000 ohm resistor and not 500 ohm?

To get a voltage drop of 9v from a source of 12v, you need 500ohm to supply 3v (fwd voltage for blue led)

ECC climate control temp sensor measurements made easier

Re: ECC climate control temp sensor measurements made easier