Alternator Startup Delay
 

Hello.

First post for me here.

I have a 1987 XJ6 named Caroline. Love her very much. Yet...she's quirky.

Have a little issue that I can't find the answer for. Maybe it's normal, maybe she's ill, I don't know.

When I turn her on, the alternator doesn't start delivering a charge until I'm down the road a little bit, usually when I hit the main road and the RPMs are raised.

Until then, her gauge sits at 10 volts, but when she "activates" the gauge goes to 13 and all is well, headlights brighten, the whole works.

Is this delay normal, or do I have some relay or something to replace.

Thanks for any info.

RE: Alternator Startup Delay
 

No response...no problem.

I've found elsewhere that there can be a protective delay built into aftermarket alternators, but it appears this delay is based on RPMs not analog time.

Any hints?

RE: Alternator Startup Delay
 

There is a single terminal lead (18 gauge, it's a small wire)that plugs into the back of your alternator...it's an "exciter" wire, and if that lead is open circuit the alternator won't start charging until engine RPM's are at least 2000. Check connection at alternator.

RE: Alternator Startup Delay
 

Is that the little silver piece that looks like a capacitor?

RE: Alternator Startup Delay
 

The capacitor is for radio supression, and has nothing to do with nothing. There is a brown/ black color coded wire with a single Lucar female spade connector: that plugs onto a male spade terminal for the alternator field winding, on the back of the alternator. If you follow it back to source, it is routed behind the A/C compressor, tywrapped to the fuel return pipe at the front of the cylinder head (along with the A/C compressor clutch feed wire and the leads to the air pump diverter valve), through the engine wiring harness to CF3 (right bulkhead multiplug), to the battery warning light on the dash.

RE: Alternator Startup Delay
 

After you've checked the exciter wire etc to make sure the charging circuit operates don't be too surprised if your voltmeter is still slow to react. Every Ser III I've driven has a lazy voltmeter. Sorta like a morning sickness type of thing :)

RE: Alternator Startup Delay
 

The"headlights brighten" comment in the original post precludes a voltmeter inaccuracy.

RE: Alternator Startup Delay
 

Good point....I missed that !

Cheers
DD