Alternator failing?

[Nightshade]

I got my diablo.. yay..

Problem.. I have noticed that the hast couple of days the car has been not starting too easily.. and the driver side HID flickers when starting..

With the engine running I get 11.3V on the EVIC.. (confirmed with a multimeter)

With the engine off it goes to 12V..

Anyone know how to test an alternator? I will try and take it in tomorrow but don't want to take all day there. Could use a hand troubleshooting...

[Mr. iNCREDIBLE]

sounds to me like the ALT failing or the belt is slipping..

you should be at 13.8 - 14.1 (depending on what electrical items are running) while the engine is at 2,000 RPM

13.5- 13.8 at idle

and 12.5 - 12.7 with engine off...


I run a solid 13.8 at all times under full load (A/C on high, stereo (2500 watts) at full, HIDs (headlights/tail-lights on) under normal load (radio at decent volume, A/C on Auto, Headlight on or off) I run 14.1 volts..

For the record I have upgraded wiring (00 gauge from ALT to battery, and 00 gauge on the Battery Ground) A Kinetic 2250 Battery and a 10 Farad Capacitor for the sound system.


definitely sounds like something is not right...


how old is your battery? What is the Voltage without the battery in the car?

have you checked the battery ground point? are any cables frayed or damaged?

[Darthvader]

I have this same issue fnky told me to have the system tested. See thread:

Starting Problem....question on battery drain

[Cam]

Double check the battery lead connection on the alternater. It may be loose or corroded.

[Nightshade]

Measuring 30 volts or so on the wire coming from the alternator. Maybe is it the regulator? Where is that located?

I guess I will go check grounds i can find.. only two that I worry about.. front and back.. don't think the others are capable of causing this....

Oh yeah.. when the car is off, I measure zero volts on the alternator terminal.. I am assuming that is good...

[Cdn_Magnum]

Joe... I was going to say something to you at Hooters about the fact when you started your car at the BAP show it didnt sound good.

The regulator is most likely built into the alternator (as it is in most cars now).
Looking at the wiring diagram (page 8W-10-7) you go straight from the battery positive terminal to the + post up front to the 'module-integrated power' and to the starter then through a fusible link to the alternator.

I suspect alternator. If you can remove it you could get it check (most likely) at KW starter and alternator off Huron Rd and Trillium Dr area (by the Bud Plant). They can rebuild them there too (usually).

[fnkychkn]

Oh yeah.. when the car is off, I measure zero volts on the alternator terminal.. I am assuming that is good...

there's your problem right there. B+ stud on back of generator should always read battery voltage. check fuse link on starter B+ stud. if it's blown, the PCM (which controls generator field through a LSD low side driver) will read low system voltage and provide full field the generator. this explains the 30 volts at the generator B+ stud while engine is running.

[Jaak]

Fnky to the rescue!

A Dog's best friend...

[Jaak]

So Pete, is that why sometimes I'll see the lights go slightly brighter then dimmer? Is it the PCM controlling the field winding ground that basically turns the generator on/off to control power output?

[Nightshade]

Wasn't a fuse.

It was the wire going from the alternator to the starter. It was WAY too close to the kooks long tube headers..

Headers + aluminum loop connector.. ugh..

The Loop connector had melted and as a result, disconnected the power...

Cost me 200 bucks to have a copper connector put on the wire and to have it reinstalled. was nasty as the bolt was partially welded due to the loose wire hitting the nut.. they got it off without breaking the stud off the alternator.. so 1.5 hours labour wasn't too painful..

I am gonna look for some header wrap for that part that is too close to the starter.. wish I had the headers coated before installing them. Maybe if I do heads/cam I will send the headers out to be coated while the engine is torn down..

[fnkychkn]

So Pete, is that why sometimes I'll see the lights go slightly brighter then dimmer? Is it the PCM controlling the field winding ground that basically turns the generator on/off to control power output?

correct Mr. Bond!

[fnkychkn]

Wasn't a fuse.

It was the wire going from the alternator to the starter. It was WAY too close to the kooks long tube headers..

Headers + aluminum loop connector.. ugh..

The Loop connector had melted and as a result, disconnected the power...

Cost me 200 bucks to have a copper connector put on the wire and to have it reinstalled. was nasty as the bolt was partially welded due to the loose wire hitting the nut.. they got it off without breaking the stud off the alternator.. so 1.5 hours labour wasn't too painful..

I am gonna look for some header wrap for that part that is too close to the starter.. wish I had the headers coated before installing them. Maybe if I do heads/cam I will send the headers out to be coated while the engine is torn down..

relatively cheap repair, considering you thought of condemning the generator. glad you're back in action.