ECC climate control temp sensor measurements made easier

[jreed]

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 8105 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 8104 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 8105 times

Side view of OBD2 connector showing 5, 6 and 16

Pin_outs_for_OBD2.jpg (52.01 KiB) Viewed 8105 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!

[jreed]

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


[YouTube][/YouTube]

[JimBee]

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

[jreed]

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]

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

[jreed]

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

[mecheng]

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)

[jreed]

Thanks for asking. It's been a couple of years and I couldn't remember, so I went down and measured the resistor with an ohmmeter. I got 5.4kOhms. That value seems to work fine with the blue LED I'm using. A lower resistance will likely also work without burning out the LED-- try 500 Ohms and see. Good luck!

[jlaakkonen]

I'm having trouble clearing the codes from my 1996 850. After I've read all the codes by clicking the button it never comes back to the first one, but just keeps blinking loooong single blinks 1(long)-1(long)-1(long)-etc ... i counted out at least ten, and then i just turned the ignition off. Therefore even though I've tried to erase the codes, it doesn't let me do it. Also an interesting thing was that it read out the first three codes one after the other without me clicking the button and then the fan turned back on, after which I clicked the button for 1 sec and then got the fourth code. Does anyone know what these long blinks at the end mean?

[jreed]

I think that the repeating "1-1-1" means that you have successfully cleared the codes.