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1994 850 temperature gauge goes up, won't start

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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Sommerfeldt
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Re: 1994 850 temperature gauge goes up, won't start

Post by Sommerfeldt »

misha wrote:Not the part with removing ecu...the part with NOT insertion it fully. :mrgreen:
Ah. Sorry. :D

- S
2018 S90 T8 Inscription - glossy black with amber interior and dark as night rear windows.
[Gone] '96 855 T5 - R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.
[Sold] '97 S70 T5
[Gone] '95 855 T5-R - one of the black ones... sadly stolen and wrecked.

charlie33
Posts: 7
Joined: 7 May 2015
Year and Model: 850 95
Location: United Kingdom

Post by charlie33 »

The socket for the ecu is like a big scart socket all i was doing was making a different contact than the one for 20 years I have now cleaned the units individual spikes and it is fully inserted but it didnt start however i took it out and gave it a flick ( not hard ) put it back in and it started so surely its the ecu if your brave take out the ecu of a 94 95 850 2.0 or 2.5 and put the ignition on 2 if the temp gauge does the same as the video ( which mine does when its out or when it feels like it when its in ) then surely its the ecu the trouble is the nearest one on ebay is latvia I am hoping im right as no mechanic or expert takes any notice of the video when the temp gauge does that, it does not start there is no power to the cps or anything else it has been checked I hope this helps someone as its cost me a fortune in time of work and i am still hoping that a replacement v.2 siemens will work everything else has been replaced if anyone can get a v.2 that would be great

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misha
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Post by misha »

Charlie33....do what you want to do,it's your car.
You didn't do most important things like measuring ect values when it will not start.
Fluctuating temp needle ALWAYS means that ect is bad.
It can also be bad intermittently.
Removing or reseting ecu ALWAYS means that ALL values are going back to factory settings.Gathered parameters are stored EVERY time the key is removed from ignition or every time the engine is switched off after driving.
After a while....when ecu gather parameters from ALL sensors it figure out that ect signal is missing or bad and it will not start again.

Thats why it always starts when you reset ecu and will not restart.
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
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

charlie33
Posts: 7
Joined: 7 May 2015
Year and Model: 850 95
Location: United Kingdom

Post by charlie33 »

The needle doesnt fluctuate when the car is running it only fluctuates when it wont start as the video shows also when it does what the video shows there is no values to test as there is no output to anything maybe i should change the ect but I dont think thats the problem thanks for all the input.

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