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Winter Mode and ECT failure?

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.

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jfry
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Winter Mode and ECT failure?

Post by jfry » Sun Oct 23, 2016 8:35 am

Hey all. Many of you have helped me with your previous posts so thanks for that. I can't find a topic with my specific problem at the moment so thanks in advance for any info or suggestions you have.

My girlfriend's 98 V70 (Base Model) started fine yesterday AM and then later in the day it would crank but not fire up. When I had a look I noticed that the "W" button was depressed. (She or one of the kids may have done that accidentally but she saw no arrow while driving so its hard to say.) I tried to press "S" or "E" and the led would light while I pressed them but the "W" button stayed lit as well as depressed. I did a bit of research on my phone and "rowed" the gearshift lever for awhile and that did not help. PNP switch is good I think as the reverse lights came on and she wouldn't turn over if in gear, only in P and N.

I disconnected the battery and waited about five minuets and depressed the brake pedal so the lights would drain any remaining power. After reconnecting she would turn over and almost catch. I tried foot to the floor for "clear flood mode" just for kicks but no luck.

Next I removed the cover on the parking brake which gave me access to the "S,E,W" switch and disconnected it. Turned the key and she fired up. Shut down, reconnected the SEW switch and she still starts. NOW you can select S and E but not W for winter mode. After reading what it can do to your transmission I'm not too upset about that but I'm wondering if it is related to my next problem, which is the thermostat reading that the engine is overheating just after a cold start.

Last fall I replaced the ECT sensor due to hard starting/no starting. (Faulty reading from the original caused the ECM to give the wrong A/F mixture.) I also replaced the thermostat at the same time. All was well until July when that sensor failed (compared temp reading on scan tool to actual coolant temp and checked its resistance) I put that down to cheap parts and replaced it AGAIN and all was well until yesterday. While I was trying to start up while stuck in "W" the fans would kick in and stay on for a few minuets after I let go of the key. After I resolved the starting issue the fans kicked on and off and stayed on with the engine cold. I went for a short drive to make sure the transmission was shifting correctly, (which it did) and the temp gauge was in the red. No engine gets that hot that quick. (Yes it has oil)

So I am wondering if the winter mode and the coolant temp sensor failures could be related? We can live without winter mode. Snow tires seem to be enough to get where we want to go. I don't want to keep having the ECT fail every few months. Have any of you been down this road before and what was the cause/fix in the end?

Thanks,

John

jfry
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Joined: Sun Oct 23, 2016 7:49 am
Year and Model: 98 V70 base
Location: Ithaca, NY
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jfry

Re: Winter Mode and ECT failure?

Post by jfry » Sun Oct 23, 2016 10:25 am

Just went out to check the ECT and again she wouldn't start, back to stuck in Winter Mode. It would almost catch and fire up and then go back to simply cranking over. I was able to start again by disconnecting the SEW switch. This time no odd temp gauge readings. It was right in the middle where you would expect after warming up at an idle.

I removed the SEW switch and cleaned it. It wasn't too bad. Going to reinstall it and see what happens. Will clean the PNP switch too. We have had a lot of rain so maybe moisture got in the connector.

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Re: Winter Mode and ECT failure?

Post by abscate » Mon Oct 24, 2016 12:55 am

TheETC connectors go bad , I wonder if you are not getting good ETC readings to the ECU.

Take a close look at RTE connector and wiring
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