Headlight/Alternator issue

[kmac33]

Okay all you electrical wizards, I need some quick help in my final preparations to have the Spider ready to drive to Freak Out. I recently upgraded the headlights and headlight wiring by installing one of IAP's Headlight Relay kits, and the Bosch H4 headlight buckets with halogen bulbs. Both installs went as expected. Installed relay kit per instructions, but had to add some wire length to the "power lead" to reach my alternator. After finishing the install, tested everything and headlights worked perfectly. Car was not driven after this upgrade as I was in the middle of other upgrades including new dash wood, etc. (Dash wood and gauges were completely out of the car when this was done).
Finally got everything back together yesterday. Doing some driving yesterday and today to fine tune steering box, get my steering wheel installed perfectly straight again, and make sure everything is good for the trip to Nashville. Start having electrical issues - funky tach, difficulty starting today (had to jump it off) so pull out the multi-meter and check volts on the battery with the car running and sure enough the alternator isn't charging, try the headlights and no headlights (all gauge lights working fine).
I checked the connection at the alternator for the "power lead" from the relay kit and it is fine, checked the 2 in-line fuses for the power lead from the relay kit and they are fine, checked all of my fuse box fuses and they are fine.
Any other ideas as to what could be going on? Only 2 days to get this sorted out!!
Thanks!

[kmac33]

Disconnected the headlight power lead from the alternator, hooked everything back up and alternator is still not charging. I didn't really think this was the culprit, but it was easy to check. This is a nearly new 95 amp alternator, so the alternator should be good. Looks like I need to figure out what could have "changed" to trigger this non charging situation, since the last time the car was driven (prior to the headlight upgrade) it was charging . I have checked all wiring connections related to the alternator such as the former external regulator wiring that needs to be bypassed and can't find anything that has come loose.

[spider2081]

Does your red battery light (in the tach) go on when the key is on but engine not running and does it go off with engine running. The battery light circuit is the power for the alternator field. It is the spade connection on the alternator. If you have a volt meter check for battery voltage on the spade connector on the alternator. If it is not there that is the problem.

[kmac33]

That may be the issue. The battery light is not coming on. Will have to check the voltage at the spade connector. Not sure what connection could now be disconnected related to the battery light circuit. Thanks for the tip.

[baltobernie]

Verify charging lamp bulb is good.
Don't know your new alt wiring scheme but some circuits require bulb to work

Bristol Bernie

[kmac33]

All gauge bulbs are new so the bulb should be fine, but will check it - you never know - thanks Bernie. Kind of amazing that Fiat would design an alternator circuit that could be disabled into a non-charging system by a bad light bulb

[kmac33]

Bernie,
A beer for you at Freak Out. It was the bulb . Still can't believe the system is configured to allow a failed bulb to knock out alternator charging!

[kmead]

Many cars are designed that way. My VW Passat stopped charging due to a bad ground in the instrument panel due to a cold solder joint of the main connector to the PCB. That was a fun one to diagnose let me tell you...

[sonosml]

Kevin,

I'm currently installing the 95 amp alt upgrade. The reason the bulb has to be good is with the bypass, the current thru the bulb is now the exciter circuit for the internally regulated alternator.

What I came here looking for was more info on the upgrade wiring. The instructions I have say to find the relay for the charging circuit bulb and pull they yellow and black wires out and connect them together. The only relay (also the one I traced back from the yellow wire at the alt) seems to have the white/black wires and looped like the wiring diagram. Except my Black wire isn't black, Maybe faded or what not, but looks blue-ish. What colors are yours.

The second thing I'm wondering is, can I just pull the relay and put a jumper wire between the yellow and black (my blue-ish) wires and leave the relay out?

IA-Mike

[seabeelt]

Before you pull the relay, remember that a small amout of voltage/current is required to trip the relay, (or hold it open) so that you are not running huge curents through other devices like the ignition switch and so forth. That is one of the reasons folks install the relay kit for the head lights.
r/

[kmac33]

IA Mike,
I would leave the relay in place as Seabeelt stated and just do the "bypass".
My "black" wire is closer to purple to my eyes, so I wouldn't be surprised if yours is no longer black either .

[baltobernie]

Still can't believe the system is configured to allow a failed bulb to knock out alternator charging!

That's why these things were known as "Idiot Lights". All manufacturers, foreign and domestic, used this scheme for many years. The bulb provides the necessary resistance in the excitor circuit to trigger the alternator charge. As I explain in my Painless article, "If the bulb is missing or defective, the alternator will not charge, nor will you have any indication of the failure. Observe the charge lamp during every start-up sequence." And if you rewire your car with a dashboard voltmeter, and eliminate the charging lamp in the excitor circuit, you'll need to install an carbon resistor of suitable value, or your alternator will run "wide open" all the time at maximum voltage, quickly destroying light bulbs, battery and the voltage regulator. Don't ask me how I know this

Note: Not all Spider model years use this circuit. Some have a separate charge lamp relay.