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Issue after battery wrong connection...

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

30CSI
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30CSI

Issue after battery wrong connection...

Post by 30CSI » Wed Dec 25, 2019 11:06 am

Dear all,
Il have one 850 from 1996, unfortunately the battery polarity was crossed... So the car does not start anymore... I have checked all fuses, all are OK, but no indication on the board panel (all lights are off) I heard the issue could be the ecu? But how I can be sure? Do you know if this car got main or central fuse to protect electronics against wrong polarity battery connection? I really want to repair my car...

Thanks for your help.

Francis

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misha
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Re: Issue after battery wrong connection...

Post by misha » Wed Dec 25, 2019 12:07 pm

No protection from wrong polarity.
What you can do is to check relays under the fuse box cover under the hood....since your intstrument cluster is dead too.
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30CSI
'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
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Re: Issue after battery wrong connection...

Post by cn90 » Wed Dec 25, 2019 4:39 pm

- Search forum, but I believe it is some kind of relay(s), nothing big...
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Re: Issue after battery wrong connection...

Post by cn90 » Wed Dec 25, 2019 4:41 pm

2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+

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Re: Issue after battery wrong connection...

Post by erikv11 » Thu Dec 26, 2019 8:16 am

Yes, what they said: check the three J relays in the fuse box at the driver's window, it is almost always one or more of them has blown. These are cheap and generic and otherwise almost never fail, junkyard is the best source.
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gone: '96 NA 850 210k, '98 NA V70 182k

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Re: Issue after battery wrong connection...

Post by abscate » Thu Dec 26, 2019 9:39 am

Thats probably the diode that protects the circuitry from spikes when the relay opens that blows on reverse polarity, but that should blow a main fuse upstream, failing closed circuit.

Ghosting erik...

Looking at the several 'reversed polarity threads' - almost all are resolved with the J relay(s) replacement, though.
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30CSI
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30CSI

Re: Issue after battery wrong connection...

Post by 30CSI » Thu Dec 26, 2019 3:14 pm

Hi,
Cn, Erik & a abscate, thanks lot for your replies and information, I removed then tests the 3 j relays, all are faulty, it seems the diodes are deads. I replaced the j by straps then all light on the pannel board were on again and I was able to start the engine... So thanks again, I found some damages on the cable to power abs motor pomp, so I have removed and opened the motor, replaced the wires, power on the motor (its working) then put it back to the abs block. I still have abs on on the dash board, may be the abs controller is dead, don't know if I can check his status trough obd socket...
Again, I'm really impressed by the level of technicity of you guys, and the amount of the tech doc available on the site... , here on a local forum nobodies were able to help me except telling me to change ecu or bring my car to the doc, or to the bin... 😁 Thanks.

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Re: Issue after battery wrong connection...

Post by 30CSI » Thu Dec 26, 2019 3:17 pm

Thanks to Misha as well 👍
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Re: Issue after battery wrong connection...

Post by cn90 » Thu Dec 26, 2019 3:55 pm

Too bad you live in Toulouse, otherwise I have a whole bunch of J relays in my garage.

Next time I am in Toulouse, I can bring them for you...

À la prochaine!
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30CSI
2004 V70 2.5T 100K+
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30CSI
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Re: Issue after battery wrong connection...

Post by 30CSI » Fri Dec 27, 2019 3:05 am

Thanks cn, so see you in Toulouse next time 👍
I found x3 30 amps relay in my mess to replace the faulty J ones, looks like OK now, just the abs is still not working despite motor cable replacement.
BR
F.

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