1998 V70 XC ECC control unit swap

Post by **scot850** » 13 Jul 2013, 00:02

Hi,

Typically, having spent a small fortune repairing my old 98 V70 XC, the old devil decided to add a new obscure problem to the mix.

From time to time in the past we would get a rubber 'squeeking' noise that sounded like it was coming from below the center console. After further investigation, it appers to actually be coming from the ECC unit, and it is becoming more frequent = annoying as time goes on. As best as I can tell, everything seems to still work ok, but if I switch the A/C off the noise goes away within a few seconds, and sometimes by switching the fan off, this will work when first option doesn't work. Any ideas what would cause this? Is it likely to be an internal short, and if so can it be repaired?

If not, I have a spare used ECC I could swap in, but I read that you have to extract data from the old unit and transfer it to the new unit. If I have a used unit, do you still have to do this? Surely, if you removed the battery, it would loose all the data in the ECC anyway? So what are the issues I may face if I just swap the units over (with fingers crossed)? I just want to prove this is the source of the problem, and if so, I will leave the other unit in if it works ok.

Appreciate any advice as usual.

Neil.

Mod note ...ECC used here to refer to the dash control unit, not the actual climate system

Post by **BEJinFbk** » 13 Jul 2013, 00:48

There's nothing in the ECC module that squeaks.
It's nothing but the controls on the front and the
connectors on the back. No "moving" parts.

FWIW - 850 and -00' 70 series ECC's are really simple units.
They have some read only diagnostics, but nothing "transfers".
They just swap in and out. Your's is probably fine.

Check damper servos, the blower motor itself or
maybe the tiny fan in the cabin temp sensor.

Post by **abscate** » 13 Jul 2013, 04:05

I would check the blower fan (pass side, through glovebox) for a squeaky bearing. Try to better see if noise is correlated with moving the fan speed selector as you note, that pointing me to the fan assembly pretty strongly.

Post by **scot850** » 15 Jul 2013, 23:36

Thanks guys. Sorry for the delay getting back, but I work weekends. I may be wrong (it happens frequently if you talk to my wife!), but the noise is more of a eee,eee,eee noise, and it seems to come from the center of the dashboard in the area of the ECC unit. I'm pretty sure it is not the fan motor as this was replaced a couple of years ago, and is quiet in use.

I'm going to try to pull the ECC unit and check the sensor fan as you suggest as well. I remember the little sensor fans in the 850 above the grab handles and when I removed those they were full of crud.

Like I say, this car always seems to find a new way to drive me nuts with obscure problems. One day I'll figure out what causes the clouds of smoke/vapor out the tail pipe when it gets cold. Again on one of those weird faults no-one can explain!

Thanks, and I'll get back on this when I figure it out. Thanks for the leads.

Neil.

Post by **JRL** » 16 Jul 2013, 06:26

Classic sound of a clogged oraface tube

Post by **jimmy57** » 16 Jul 2013, 08:58

Or is it the in car temp sensor's little fan motor. That is next to the ECC in the far right of the strip where accessory switches mount. It could sound like it comes from the ECC.

lexmia · Post by **lexmia** » 22 Mar 2018, 15:22

I know this is an old thread, but thought it would be nice to have the information from the Volvo service manual stated in here:

The ECC stores the following information, and not every item in every ECC controller variant. These values must be read from the old ECC and programmed into the new one:
- Driver's position: Left or Right hand side
- Engine Type: Diesel or Petrol, to compensate for heater capacity
- Presence of in cabin filter or not.
- Cabin temperature compensation adjustment +/- 2 C, in 0.5C steps
- Blower fan speed compensation adjustment between +/- 8 liters/sec, in 4 lt/sec increments
- Sun Sensor sensitivity compensation, for some ECC modules, 7 stages, from -4 to +2
- Speedometer signal (for some ECC modules), that comes from the instrument cluster, depending on whether you have a fuel gauge that reads MAX (newer) or a numeric figure such as 18 gallons (older). The pulses fed from the cluster are either 48 (older) or 12 (newer). Newer ECCs (from production week 832) are capable of working on both systems, but need to be programmed.

There are many different ECC modules, that look the same outside, but are different inside. Most should work interchangeably

Post by **scot850** » 22 Mar 2018, 15:27

Thanks for the excellent info. Just realised that I never closed this off! It was eventually tracked down to a bad servo motor on the 98 V70XC which I found just before selling it. After swapping it for a spare one I had all was quiet!

Neil.