Blue exciter wire- 83 GTi - charging problems

[frankie m]

I have been searching and reading alot. I still have to test terminal 11 and 13.

Car has new battery ( 1 year) and new alternator ( about 3 months).

Car was running fine but then i noticed that the stock volt gauge was not showing past 12 anymore.

On the way home the other day- battery light came on and stayed on until I rushed home ( about 13 minutes or so).

Car started after shutting it off- BUT when I started it up again, the battery light would not come on at start up.

I checked the battery voltage with my tester and it was around 11.73 and it would not budge when I accelerated so its obvious that the alternator is not charging----I checked the alternator plug and its ok---its held in with original c clamp. I dont think its the alternator bc my mechanic got a rebuilt Bosch unit--but I could be wrong----Im thinking blue exciter wire.

Today, battery light came on and stayed on...

Recently (about 2 weeks ago, car was at the shop- my mechanic changed blower motor and odometer gear-so dash and cluster were apart- so maybe the blue exciter wire was moved?)

Where do I go from here in troubleshooting-- Car has always had this problem with the voltage- battery was changed 3 times and alternator 2 times......Now I want to make sure that the blue exciter wire is not broken in any place.....Where can I buy a new blue exciter wire?

I have been reading but still a little confused---can somebody explain to me the function of this blue wire? -- I know that its connected to cluster & sends signal from alternator to red battery light --But how does it send the signal for alternator to charge? Can somebody post a wiring diagram of this blue exciter wire? ---going to Bentley now.....Thanks
Any tips? Thanks

Oxygen sensor light has never worked in my car---8 years

[jason08]

I had a similar issue a couple years back with rabbit loosing charge, went through a couple alternators and a new battery. I double checked the blue exciter wire several times but found no broken or loose connections, turned out to be my battery light in my dash, because the light failed the alternator was not getting the signal, my mechanic rigged up a different light as a temporary fix and it completely fixed the problem; but you mentioned that your battery light has been coming on so maybe it has nothing to do with this,
Hope someone can chime in with some more suggestions.

-J

[rabbitnothopper]

replaced my light with an LED...wont burn out now suckah

reminder that LEDS require a resistor to operate properly.

it is mystifying but the blue wire actually goes through the fusebox into the bulb

mr kamzcab i think has a fancy pinout of the whole process


have you replaced the Voltage Regulator yet?
those tend to wear out

if you keep wearing out Voltage Regulators then time to dump some dollars on a few remanufactured Altenators until you find one that doesnt burn up in a few years of use

[rabbitnothopper]

dude totally random oxs light never worked on your car?

the only thing the oxs light does is indicate a set period of time travelled since it was last reset
an indicator telling you to replace the o2 sensor

o2 sensors are what..50,000 mile replacements?

depending on your cluster and speedometer cable setup (egr box) you may have a mechanical counter inside the cluster or an electronic counter, or some other thing happening

i should photograph my old mechanical oxs gears...

[frankie m]

Thanks for answering - I was reading that the blue exciter wire is also connected to the oxygen sensor light-----I have never seen that light on at start up----not sure if it is suppose to turn on at start up?

Going to take out the cluster today and then bring it to my mechanic tmro.
Anybody know what gauge wire it is? Wheres the best place to buy this?

[rabbitnothopper]

only battery and oil are supposed to turn on when key is "ON"

[Esevw]

Blue exciter wire connects to big blue harness plug and then runs to second yellow plug behind the first box. I'm on my cell and can post pics tomorrow. I am currently re-wiring my gti.

[frankie m]

Thanks for all the replies.

Looking forward to pictures.

Thank You

[Esevw]

Here is the picture of the plugs, not the best, took them with my cellphone. You can see the blue wire in both of the plugs.
You should find the plugs and check the wire for continuity to make sure that it is not broken anywhere. Unplug the wire first from the alternator before checking it.
blue plug
https://www.dropbox.com/s/poondcast1...008_141941.jpg

yellow plug
https://www.dropbox.com/s/zq95fwyndh...008_141815.jpg