MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: Gaz2405 on September 14, 2023, 20:13

Title: Alternator not charging
Post by: Gaz2405 on September 14, 2023, 20:13
I've posted this on the FB group too.

Really struggling here.

I suspected a bad alternator as I was getting intermittent charging, so swapped it out.

Now I'm getting no charge from a brand new alternator.

All grounds are fine, check by adding extra etc.

I think I've tracked it down to the 7.5a gauge fuse in the passenger door, as that also has input from the charging side.

Any ideas anyone?

Title: Re: Alternator not charging
Post by: mr2garageswindon on September 15, 2023, 10:40
Fuse no 9 in engine bay fuse box? 7.5A
Title: Re: Alternator not charging
Post by: Gaz2405 on September 15, 2023, 10:46
Quote from: mr2garageswindon on September 15, 2023, 10:40Fuse no 9 in engine bay fuse box? 7.5A

That's all good too.
Title: Re: Alternator not charging
Post by: mr2garageswindon on September 15, 2023, 10:49
What make is the alternator? Not RTX or voltron etc?
Title: Re: Alternator not charging
Post by: Carolyn on September 15, 2023, 11:49
I must confess, I was thinking you might just have bought a duff alternator.  It does happen.
Title: Re: Alternator not charging
Post by: Gaz2405 on September 15, 2023, 13:13
Quote from: Carolyn on September 15, 2023, 11:49I must confess, I was thinking you might just have bought a duff alternator.  It does happen.

I've had another delivered today, so will try that.

Would a duff alternator blow the gauge fuse though?
Title: Re: Alternator not charging
Post by: Gaz2405 on September 15, 2023, 18:46
Ok, plot thickens....

With the dash plugged back in, it still blows gauge fuse, on the 2nd click of the ignition.
Title: Re: Alternator not charging
Post by: shnazzle on September 15, 2023, 23:04
My brand new eBay alternator lasted a few months.
Got a 2nd hand Toyota OEM and all was good.

Another one of those components best kep as OEM I guess
Title: Re: Alternator not charging
Post by: Alex Knight on September 16, 2023, 12:13
Quote from: Gaz2405 on September 15, 2023, 18:46Ok, plot thickens....

With the dash plugged back in, it still blows gauge fuse, on the 2nd click of the ignition.

Bad earth somewhere?
Title: Re: Alternator not charging
Post by: Joesson on September 16, 2023, 13:11
Quote from: Gaz2405 on September 15, 2023, 18:46Ok, plot thickens....

With the dash plugged back in, it still blows gauge fuse, on the 2nd click of the ignition.



Not very helpful but I had a very similar issue in the 80's with a new Vauxhall Cavalier. No instrument s and two fuses would have to die before the car would run with instruments. Only happened first thing in the morning. Didn't happen for the main dealer! who suggested it could be a rogue Earth/ a stray wire grounding.
It eventually cured itself, that may agree with the rogue Earth suggestion.
Title: Re: Alternator not charging
Post by: normanh on September 16, 2023, 17:47
Alternators wont work unless you put 12V onto the slip ring - usually the small spade connector so its worth checking that as well as the earth for continuity. If ok then I would suspect a duff one.

Norman
Title: Re: Alternator not charging
Post by: Gaz2405 on September 17, 2023, 18:51
Fixed!! Break in the middle wire (red with a thin black line) somewhere in the harness. Tested it with a jumper wire to the orange connector behind the passenger seat.  Panic over.