1997 850R ECC Reset Procedure

nateyaro · Post by **nateyaro** » 18 Jan 2015, 09:57

Hello everyone.

I've been on a hunt to try and figure out how to reset the ECC in my 97 850R.
I spent most the day yesterday trying to figure out a solution.

I'd prefer not to go in and pay the dealer to reset it.
Some of my findings have gone as follows.

1) Vol-FCR would be a great solution for my car (if I wanted to spend $150 but I don't.

2) The LED light and resistor rig works on some cars to read and reset the ECC but not ALL of them.
I think mine since its a 96+ and is the R is one of the ones that fall into that category. (I would prefer to be told if it works or not before trying to rig everything up) http://www.volvoforums.org.uk/showthread.php?t=83895

3) http://www.volvo850diag.html seems promising as I already have this OBDII adapter https://www.amazon.com/gp/product/B00B3K2X4M/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1 However I messed with this method all day yesterday, literally installed windows on my laptop so I could try and get it to work but I'm starting to think I am just not smart enough to make that method work.

I really don't know what other methods are out there aside from taking my car back into the shop.
I just know I currently don't have defrost and after replacing one of the damper motors (that's supposed to control defrost) and the ECC unit itself, now everything needs reset. I honestly didn't think this would be the hardest part.

If anyone has any pointers I would love to hear them!

Thank you,

Post by **misha** » 18 Jan 2015, 10:21

Ecc unit on 850(s) still produce the flash codes,so Vol-fcr will not help you on this.

Home build flash code reader is the way to go.

Leave it without power for a while(10-15min)and that should reset it.

If there is a permanent fault stored,you can't reset it untill it is solved.

nateyaro · Post by **nateyaro** » 18 Jan 2015, 10:51

misha wrote:Ecc unit on 850(s) still produce the flash codes,so Vol-fcr will not help you on this.

Home build flash code reader is the way to go.

Leave it without power for a while(10-15min)and that should reset it.

If there is a permanent fault stored,you can't reset it untill it is solved.

What do you mean by leave it without power for 10-15min? As in un plug the battery? or unplug the ECC?

Post by **misha** » 18 Jan 2015, 11:04

Try with ecc first.

If you disconnect battery you will reset fuel trim adaptives.

Post by **jreed** » 18 Jan 2015, 16:36

I've got the '97 855 GLT but the little home-brew code reader definitely works to reset the codes in the ECC. You have to be sure to read through all of the codes until the first one repeats, and then you can reset all of them. I wrote up a short guide to building and operating one of the code readers here:
https://www.matthewsvolvosite.com/forums ... 43#p251189

nateyaro · Post by **nateyaro** » 18 Jan 2015, 17:58

jreed wrote:I've got the '97 855 GLT but the little home-brew code reader definitely works to reset the codes in the ECC. You have to be sure to read through all of the codes until the first one repeats, and then you can reset all of them. I wrote up a short guide to building and operating one of the code readers here:
https://www.matthewsvolvosite.com/forums ... 43#p251189

That makes a ton of sense. Thanks for posting it. I was wondering however, Where does the resistor going in the assembly? I see the switch and I see the LED but I don't see the resistor.

I think once I have that I can get it done.

Thanks again!

Post by **jreed** » 18 Jan 2015, 18:32

Thanks for asking! The resistor is hidden underneath the longer section of blue heat shrink tubing next to the LED. You can put the resistor on either the + or - terminal of the LED. The resistor serves to limit the current through the LED.

Post by **esl_97_850_T5** » 22 Jan 2015, 15:54

1. If you buy RadioShack Red LED Assembly w/ Built-in Resistor, part # 276-0270 ($1.99 + tax), the resistor is built-in to the LED, thereby eliminating the need to add a separate resistor to the circuit.

2. Using "ac heater system auto.pdf" of 1995 Volvo 850 Service Manual as a guide, I was able to get the following working for my '97 850 T5:

- TEST MODE 1 (reading the ECC DTCs). Very consistently.
- TEST MODE 5 (clearing the ECC DTCs), though I think I held the flashing LED tool's pushbutton down for more like 6-7 seconds each time. Only worked some of the time.

I think I got this one to also work:

- TEST MODE 4 code 9-9-9 (self-adjustment of damper motor limit positions [8-8-8 might also work]).

But I could not seem to get the expected responses from:

- TEST MODE 2 (check that solar sensor is OK and check that speed signal from COMBI is OK). Never saw the rapid flashing.
- TEST MODE 4 code 1-1-1 (controlling A/C relay). TEST MODE 4 was entered, but 1-1-1 didn't produce any A/C indicator lights going on and off, and there was no audible relay clicking. Yet I can hear the A/C relay clicking on and off during its normal operation.

Note #1: Entering the 3-digit codes in TEST MODE 4 works a bit differently as far as the feedback and timing of the lights.

Note #2: There's also an HTML equivalent of "ac heater system auto.pdf" that can be found by searching for "Air conditioniong ECC / Climate Control & heater system repair manual" on this volvotips page, then clicking that line.

3. Concerning volvo850diag...

The volvo850diag - ELM327 combo will never be able to talk with the '96-'97 850 ECC. The very low baud rate communication of the flashing LED tool is very inconsistent with the 10400 baud communication that the volvo850diag - ELM327 approach uses.

The volvo850diag - ELM327 combo can, however, be used to read/clear ECC DTCs for '98 S70/V70. But kwpd3b0_interpreter (as of today, 2015-01-22) will interpret only a few of the ECC codes.

4. My understanding is that, for the foreseeable future,

a) flashing LED tool is the preferred DIY method for 1996-1997 850 ECC DTC reading/clearing (and might be usable to perform the self-adjustment of the damper motor limit positions), and

b) Vol-FCR - VAG/COM KKL is the preferred DIY method for 1998 S70/V70/C70/XC70 ECC DTC reading/clearing.

5. jreed's ECC oriented threads viewtopic.php?f=1&t=50443 and viewtopic.php?t=50525 are quite informative.

esl_97_850_T5

Post by **jreed** » 22 Jan 2015, 18:47

Wow! Thanks! That link you posted is great! I had no idea that the service manual was available online for the 850!

http://www.volvotips.com/index.php/850- ... ir-manual/

Post by **misha** » 22 Jan 2015, 19:03

jreed wrote:...I had no idea that the service manual was available online for the 850!...

For a past few years.