Nissan Primera P12 Alternator fuse melting 120A

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   54 plate P12 2.2 dCi diesel Estate 152,000 miles

Car went into limp home mode on a short run the other night, loss of power, would not rev, strange as I was driving it steadily. Pulled over and restarted, fine, all ok.

Next day after another relatively short steady run 5 / 6 miles went into limp home mode again.

Checked NPOC forum, decided to fit extra earth wire via rear light. Also decided to clean connections of earth strap between car body and starter motor. (this was fitted some years ago by local garage when car failed to start, a common problem and this fixed it).

I had disconnected battery before working on wiring, checked fuses and found brown 120A (alternator fuse? ) had badly melted although still working (Brown fuse at top in small fuse box, next to battery on left).Luckily I had a spare and fitted new one.

A few years and maybe 5000/6000 miles ago this 120A kept blowing (possibly after having clutch replaced at garage). I think I cleaned connections of earth strap and this seemed to cure blowing problem but fuse was working "warm" and plastic discoloured, I wasn't too bothered because it was working ok.

Now the airbag warning is flashing, I had cured this nuisance problem by disabling electric seat and locking glove box but made the mistake of opening glove box to store paperwork of my Primera "Fixes" including reset procedure for airbag!

I have now tried many times to reset airbag but no luck. I will keep trying, its a bit complicated and sensitive. I also attempted ECU reset, it may have worked as car is so far running ok.

Any advice regarding slowly melting 120A fuse would be appreciated. 

I thought about getting a higher 140A replacement use but maybe not a good idea?    

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Babygodzilla Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 08 Feb 2016 Location: Warwick Online Status: Points: 17	Post Options Post Reply Quote Babygodzilla Report Post Thanks(0) Quote Reply Topic: Nissan Primera P12 Alternator fuse melting 120A Posted: 03 Feb 2019 at 1:43pm
	54 plate P12 2.2 dCi diesel Estate 152,000 miles Car went into limp home mode on a short run the other night, loss of power, would not rev, strange as I was driving it steadily. Pulled over and restarted, fine, all ok. Next day after another relatively short steady run 5 / 6 miles went into limp home mode again. Checked NPOC forum, decided to fit extra earth wire via rear light. Also decided to clean connections of earth strap between car body and starter motor. (this was fitted some years ago by local garage when car failed to start, a common problem and this fixed it). I had disconnected battery before working on wiring, checked fuses and found brown 120A (alternator fuse? ) had badly melted although still working (Brown fuse at top in small fuse box, next to battery on left).Luckily I had a spare and fitted new one. A few years and maybe 5000/6000 miles ago this 120A kept blowing (possibly after having clutch replaced at garage). I think I cleaned connections of earth strap and this seemed to cure blowing problem but fuse was working "warm" and plastic discoloured, I wasn't too bothered because it was working ok. Now the airbag warning is flashing, I had cured this nuisance problem by disabling electric seat and locking glove box but made the mistake of opening glove box to store paperwork of my Primera "Fixes" including reset procedure for airbag! I have now tried many times to reset airbag but no luck. I will keep trying, its a bit complicated and sensitive. I also attempted ECU reset, it may have worked as car is so far running ok. Any advice regarding slowly melting 120A fuse would be appreciated. I thought about getting a higher 140A replacement use but maybe not a good idea?

Babygodzilla Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 08 Feb 2016 Location: Warwick Online Status: Points: 17	Post Options Post Reply Quote Babygodzilla Report Post Thanks(0) Quote Reply Posted: 03 Feb 2019 at 4:14pm
	Looking online for answers today and its possible my alternator may be faulty and overcharging battery? Everything seems to be working electrically as it should. The battery is about 2 or 3 years old , Varta 74Ah 680A heavy duty job. Its possible the alternator has a poor earth connection and this is causing the slow melting of the 120A fuse? I will have to take a look at the alternator and figure out if the wiring looks OK but not sure what to look for. Unfortunately I am no mechanic, I may have the answer but if anybody can advise I would appreciate the help.

imckay Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Member Joined: 11 Mar 2007 Location: Manchester Online Status: Points: 3374	Post Options Post Reply Quote imckay Report Post Thanks(0) Quote Reply Posted: 04 Feb 2019 at 7:12am
	Can't help with why the Fuse is popping. Would suggest an Auto Electrician. The Airbag Light is commonly caused by the Connector under the Front Seats or behind the Glovebox. Unplug and replug a few times to clean the connections up. Service Manuals. You want P12.zip. See the SRS Section http://www.npoc.co.uk/forum/nissan-primera-factory-service-manuals_topic29493.html

Babygodzilla Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 08 Feb 2016 Location: Warwick Online Status: Points: 17	Post Options Post Reply Quote Babygodzilla Report Post Thanks(0) Quote Reply Posted: 04 Feb 2019 at 7:53am
	Thanks for the help, I will try connections

Babygodzilla Members Profile Send Private Message Find Members Posts Add to Buddy List NPOC Guest Joined: 08 Feb 2016 Location: Warwick Online Status: Points: 17	Post Options Post Reply Quote Babygodzilla Report Post Thanks(0) Quote Reply Posted: 07 Feb 2019 at 8:03am
	Car running fine now, decided after a decent run in rush hour traffic while car was warm to attempt reset without touching wiring.Got it right 1st time, maybe a few days and just being persistent is the answer? Ordered spare 120A fuses, the replacement is working "warm" near it's limit,clear window of fuse discoloured, looks like it's been baked in an oven.When I get time I will check alternator connections.If anyone has had this happen before please let me know.