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98 S70 ECC only works when hot or after 30 min

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

TexasT5
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98 S70 ECC only works when hot or after 30 min

Post by TexasT5 » Fri Jun 05, 2020 7:18 am

Greetings,

First time posting here but have been grateful for the info on this site over the years. I have a 98 S70 T5 I bought brand new and picked up at the factory, which now has 190,000 miles and went through my wife, me, 2 boys, and back to me again.

Been having problems with the ECC but finally seems to have a recognizable pattern. On a day less than 86 degrees, when I start the car there is no activity or lights from the ECC. After driving the car for 20-30 minutes it will usually start and behave normally. At times that the temperature reading on the dash is 86 degrees or higher, it will work right away. No flashing lights.

So far, I have cleaned the dash temperature sensor twice and replaced the ECC with a junkyard unit. Neither of these affected anything.

Any ideas where to start? Thank You in advance.

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manovlov
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Re: 98 S70 ECC only works when hot or after 30 min

Post by manovlov » Sun Jun 07, 2020 1:04 pm

Hy,

Manov, newbie.

Could it have something to matter with the Mass air flow or the camshaft sensor ?
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Manov
Vroum !

TexasT5
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Re: 98 S70 ECC only works when hot or after 30 min

Post by TexasT5 » Sun Jun 07, 2020 1:17 pm

Hi,

Thanks so much for responding. Car is running great but I am open to checking anything out. Just the Electronic Climate Control (ECC) that is working intermittently.

T

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misha
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Re: 98 S70 ECC only works when hot or after 30 min

Post by misha » Sun Jun 07, 2020 1:54 pm

manovlov wrote:
Sun Jun 07, 2020 1:04 pm
Hy,

Manov, newbie.

Could it have something to matter with the Mass air flow or the camshaft sensor ?
Capture d’écran 2020-06-07 à 21.00.59.png
Capture d’écran 2020-06-07 à 21.04.04.png

Manov
Nope!
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

scot850
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Re: 98 S70 ECC only works when hot or after 30 min

Post by scot850 » Sun Jun 07, 2020 3:12 pm

For issues like that it is probably best to get the fault codes read. While these are not always 100% accurate, they will mostly point towards a probable source of the issue.

You have changed the 2 main components. There was a change if I recall from 98 to 99 in the ECC, hopefully one of the other guys will chime in to confirm or deny!

Did you test the cabin temp sensor to make sure the little can is moving freely and spinning? I use a 9V battery and 2 leads to check if it spins ok. If this is not working then the ECC won't.

The fact that it is temperature dependent means it is most likely a bad connection or failing fuse or circuit board somewhere.

Try swapping the fuse out and look carefully at the pins on it. Look for burning or heavy oxidation. I'd swap it anyway just to eliminate it as an issue.

Neil.
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2000 V70 R - still being an endless PITA
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2003 Toyota 4Runner V8 Limited
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1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold

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Re: 98 S70 ECC only works when hot or after 30 min

Post by misha » Sun Jun 07, 2020 3:32 pm

I got an impression from it's description that it's ECC doesn't even have a power until the car gets hot.

Siezed cabin temp sensor will not prevent blower to work,Neil.

The only fault which can prevent blower to work is power stage fault.

ECC doesn't get a power until 20-30 min after startup.Fuses should be checked,relays and wiring diagrams to see where it gets power from.
I would say ignition switch....but it would affect all other things...not just ECC.

And correct....you MUST find '98 (U.S market)replacement ECC module...'99 & '00 will not work.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

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Re: 98 S70 ECC only works when hot or after 30 min

Post by scot850 » Sun Jun 07, 2020 4:38 pm

Thanks misha. I knew I could rely on you correct my memory lapses!

Neil.
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2003 Toyota 4Runner V8 Limited
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1997 Volvo 850 SE NA - Went to niece in California - Sold
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Re: 98 S70 ECC only works when hot or after 30 min

Post by Clemens » Mon Jun 08, 2020 2:05 am

+ 1 on the ignition switch. Totally worth it because this is a wear item that can cause alot of electronic gremlins.
Then, if that doesn't help, get a replacement ECC unit. They do fail from time to time. I had it happen on my 854.
Summer: 1996 855 R
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TexasT5
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TexasT5

Re: 98 S70 ECC only works when hot or after 30 min

Post by TexasT5 » Mon Jun 08, 2020 9:10 am

Thank you to all!

That is correct that it doesn't have power at all until 20-30 minutes - or - outside temperature greater than 86 deg.

I'm afraid I may have gotten the wrong ECC as I just grabbed the best looking one out of a junkyard V70 T5 (same body style) and didn't pay attention to the year. Mistakenly assumed they were all the same. BUT, it doesn't act any differently with the original one or the junkyard one. Possible that the JY ECC is bad also.

So.....I need to build a code reader and query for ECC trouble codes
..........Good shakedown / inspection of fuses and wiring. Find wiring diagram.
..........Consider changing ignition switch, I also think that more than the ECC would be erratic but crazier things have happened.

I'll report back when done.

Thanks again. Stay safe all.

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Re: 98 S70 ECC only works when hot or after 30 min

Post by misha » Mon Jun 08, 2020 3:13 pm

No flash codes on ECC from s,v70....they are fully obdII.
850 in '97 was the last one which ECC produce flash codes.

You will need at least Vol-fcr.

BUT...since the ECC doesn't even have a power for a few minutes....you will not be able to communicate with it.
There must be a relay for powering ECC,find it.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
'71 144 S
'73 144 De Luxe
'78 244 DL
'78 244 DL
'79 244 GLE
'85 340 GLS

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