98-2000 ECC Cold Temperature Issue, 9171800 intermittent

Post by **FlyingVolvo** » 17 Dec 2020, 20:40

Hello, I'm trying to find out more about an issue I've been experiencing lately, along with some other people I know. Basically, if my car (2000 XC) is left out overnight at ambient temps of freezing or below, the ECC (climate control) will not power on for about around 5-10 minutes. No lights, no sounds, nothing. No stored codes in VIDA. Just dead. Doesn't matter if I restart the engine, jiggle or cycle ignition, reset battery cables, pull and reset fuses... nothing. The only thing that ends up working is waiting, and legitimately anywhere from 5-10 minutes later, it powers on and works totally fine.

I have a friend who has the same issue in his 98 T-5 and he knows of a few others that have experienced it as well. I believe he also swapped ECCs and had the same problem.

Any idea what this could be about? One of the few things that's stumping me. I've got a project 97 850 T-5 in the garage, so the XC has been freezing out at night and this issue happens every morning. Sadly, my commute is about 10 minutes, so it's been chilly.

Thanks!

Post by **abscate** » 18 Dec 2020, 02:59

Try bringing th unit in from the cold to see if you can isolate the problem to the ECZc control unit

Plug in before powering up, of course , standard good electronics practice.

I believe the 9171800 control unit is 1998 1999 2000 only?

Not hard to find, I might have one in my parts bin

thrich · Post by **thrich** » 11 Jan 2021, 18:07

Same issue with my 2001 C70. In cold weather the ECC is just completely dead, no lights and no communication with VIDA either. After a while it will usually start working. Didn't have this problem in the summer. I swapped an ECC from a 2000 C70 -- this one did not power up either. I checked all the ECC related fuses in the fuse box under the hood. I've got an extra ECC on the bench now to investigate. I don't have the 2001 item right now to confirm (car driven off out of town) but I recall the part numbers were the same for the two units from a quick look I did when both were out.

Post by **wizechatmgr** » 11 Jan 2021, 18:13

Now I think I'm going to pull my "semi functional" ECC out of my trunk and re-solder the connections for giggles. My guess is there is a power regulator on the B+ feed going to it and it gets cranky as it gets old. That or an electrolytic capacitor on the same stage failing... If I remember correctly, they hit some of this up with conformance coating... Not sure why as it should never get wet...

Post by **FlyingVolvo** » 11 Jan 2021, 19:22

I'm still trying to figure this out, but I've working on my 850 too much! Irritating for sure, and embarrassing for a car forged in the cold.

Post by **FLXC90** » 11 Jan 2021, 20:26

I like the take the LRU in the house overnight, that may determine whether the problem is in the box, or the circuit. Or pay a crew chief to bring you a heater!!

Post by **BEJinFbk** » 14 Jan 2021, 19:50

Long shot, but there are also a few power contacts in the string.
Ignition switch and the accessory overload relay that it energizes.
Anything else inop while you wait for the ECC to wake up?

Post by **FlyingVolvo** » 14 Jan 2021, 20:01

BEJinFbk wrote: ↑14 Jan 2021, 19:50 Anything else inop while you wait for the ECC to wake up?

Nope. Everything electronically is 100% good to go that I'm aware of. Just the ECC is straight up de-powered. Anything that I should check in particular?

Post by **scot850** » 14 Jan 2021, 20:54

If I recall, the A/C in the P80's does not work under about 10C. So if you have the A/C enabled it may have an over-ride in place until the cabin temp gets above that. Have you tried running the heating on manual rather than auto with the A/C dis-abled?

Neil.

Post by **abscate** » 15 Jan 2021, 04:37

I think the whole unit Is electrically dead until it warms up, reading the top post.

11C/32 is the main fuse feed for the ECC CONTRIL UNIT, per the diagram

Pin C5 on the bus