Why would they wire it this way
- Thread starter turbotod
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BlackMetal
Active Member
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- Sep 29, 2005
I believe it's supposed to be a resistor type bulb where current can still pass even if it burns out. Someone may have installed the wrong type of bulb, and then it will be an issue.
BlackBandit
God loves Buicks!
- Joined
- Mar 29, 2003
turbodave231
Moderator
- Joined
- May 24, 2001
If you bypass the bulb, you will burn out the voltage regulator. You need the resistance of the bulb in that circuit.
Dave
Dave
The bulb is dual purpose; it tells you if there is a fault in the charging circuit. Notice the bulb is illuminated when the engine is not running, key on. Once the alternator spins, the bulb goes out.
That is the very reason you don't hard-wire that circuit. The instant you turn your key on, the regulator - which puts out a ground until the alternator spins - would then get full 12 volts to that ground and burn it out.
The bulb in the dash provides just enough current to energize the field winding in the alternator, which then makes it produce voltage. Some Regals have a "resistor" bulb socket, which would kick in if the bulb were to burn out.
The Field Fix harness bypasses the "dead bulb dead battery" scenario.
Here is some information regarding the dash cluster. Although it centers around the digital dash option, there is some interesting info in the article regarding the bulbs, particularly the charging VOLTS bulb:
http://www.installationinstructions.com/FYI/digitaldash.pdf
That is the very reason you don't hard-wire that circuit. The instant you turn your key on, the regulator - which puts out a ground until the alternator spins - would then get full 12 volts to that ground and burn it out.
The bulb in the dash provides just enough current to energize the field winding in the alternator, which then makes it produce voltage. Some Regals have a "resistor" bulb socket, which would kick in if the bulb were to burn out.
The Field Fix harness bypasses the "dead bulb dead battery" scenario.
Here is some information regarding the dash cluster. Although it centers around the digital dash option, there is some interesting info in the article regarding the bulbs, particularly the charging VOLTS bulb:
http://www.installationinstructions.com/FYI/digitaldash.pdf
It says the charging bulb has a 470 ohm resistor across the contacts. I almost was forced to have my car towed 80 miles due to what I'm being told the bulb and/or socket. I'd almost rather install the right resistor soldered in to keep it going full time instead of it coming loose and causing problems.
John, I've been tossing around the idea of getting one of these modules along with a couple of other things from Casper's for a while now. I've got a question now though after reading the description again--it says this module "plugs into the wastegate connector and alternator". By "wastegate connector" I'm assuming it means the wastegate solenoid connector. I ditched my stock wastegate solenoid quite a while ago since I'm running an external wastegate and manual boost controller so I have the connector tucked away somewhere (still attached to the wiring harness but out of sight, and the solenoid is in my spare parts bin in the garage). Does it matter if the solenoid is not it use/not installed? Also, just curious--what's this thing got to do with the wastegate anyway? TIA...
It's supposed to keep the alternator's field windings energized in the event that the bulb burns out, thereby keeping you from being stranded by a bad light bulb. How it accomplishes this by being plugged into the wastegate solenoid plug is beyond me though...waiting for an answer on that myself.
novaderrik
Well-Known Member
- Joined
- May 12, 2004
the GM engineers wired it that way so the idiot light would tell the driver that something was wrong in the event that something went wrong.
it says right in the owner's manual that if the light doesn't come on with the key on and engine off, then there is a problem that needs to be addressed.
and we all verify that the proper lights come on before we start the engine- right?
sometimes, it's a dead alternator. other times, it's a dead bulb- but usually, it's a bad connection where the cluster plugs into the dash harness.
it says right in the owner's manual that if the light doesn't come on with the key on and engine off, then there is a problem that needs to be addressed.
and we all verify that the proper lights come on before we start the engine- right?
sometimes, it's a dead alternator. other times, it's a dead bulb- but usually, it's a bad connection where the cluster plugs into the dash harness.
rodman99999
Active Member
- Joined
- Mar 25, 2004
Well let's see: The alternator field requires a certain amount of exciter voltage that is supposed to be provided through the bulb. Any electrical solenoid(such as the stock wastegate controller) requires voltage to operate. The kit in question is supposed to supply the field with the proper voltage, should the bulb fail, and requires voltage to do that. The Wastegate solenoid connector was probably the easiest/most convenient source of ignition key controlled(via the ECM/SOL fuse) voltage.
rodman99999
Active Member
- Joined
- Mar 25, 2004
No such bulb exists. When the filament burns out, the bulb is an open circuit.
BlackBandit
God loves Buicks!
- Joined
- Mar 29, 2003
Not true. How do you think those Christmas lights work that if the bulb burns out only one light goes out but if you pull the socket about 20 lights go out? I don't think that's the type of bulb the circuit is designed to use and I'm not entirely sure they're called resistor bulbs, but they do exist.
Edit: FWIW I think the part in that type of bulb is called a shunt. I remember seeing it on an episode of how stuff works or history of the Christmas light or something like that.
OK, I'll simplify it. The bulb is a standard dash illumination bulb, but *some* cars use a special bulb socket with a resistor built into it. The reason is, if the bulb burns out, the resistor takes over. Well, that's theory.
Now, some reality.
The fault only sometimes lies in the bulb itself. Most of the time, though, it's the socket and/or the flex PC board that makes the attachment to the wiring harness, and ultimately, to the alternator. If the flex board fails (and I've seen many failures with them) then even if the bulb is working, the circuit is interrupted in-between the alternator and the power source - so you call the flatbed.
The FieldFix harness bypasses the bulb using another circuit within the alternator's regulator. It simply picks up power from the positive feed on the WG SOL circuit, so even if you don't use a wastegate solenoid, you can still use its connector for a power source, then route it to the proper input of the regulator. This positively assures that the alternator will put out a charge when the engine is running.
Unless, of course, the SOL fuse is burned out. Then all bets are off.
The FieldFix is a good thing to have, and cheap insurance. Especially if you already have called the flatbed to get your car, or been through the usual "maybe it's the alternator, I'll just replace it" and "maybe it's the battery..."
Now, some reality.
The fault only sometimes lies in the bulb itself. Most of the time, though, it's the socket and/or the flex PC board that makes the attachment to the wiring harness, and ultimately, to the alternator. If the flex board fails (and I've seen many failures with them) then even if the bulb is working, the circuit is interrupted in-between the alternator and the power source - so you call the flatbed.
The FieldFix harness bypasses the bulb using another circuit within the alternator's regulator. It simply picks up power from the positive feed on the WG SOL circuit, so even if you don't use a wastegate solenoid, you can still use its connector for a power source, then route it to the proper input of the regulator. This positively assures that the alternator will put out a charge when the engine is running.
Unless, of course, the SOL fuse is burned out. Then all bets are off.
The FieldFix is a good thing to have, and cheap insurance. Especially if you already have called the flatbed to get your car, or been through the usual "maybe it's the alternator, I'll just replace it" and "maybe it's the battery..."
rodman99999
Active Member
- Joined
- Mar 25, 2004
Not true. How do you think those Christmas lights work that if the bulb burns out only one light goes out but if you pull the socket about 20 lights go out? I don't think that's the type of bulb the circuit is designed to use and I'm not entirely sure they're called resistor bulbs, but they do exist.
Edit: FWIW I think the part in that type of bulb is called a shunt. I remember seeing it on an episode of how stuff works or history of the Christmas light or something like that.
OK- You got me! I'm Jewish, and our Chanukkah bush didn't have blinking lights, just candles. All seriousness aside though: No such bulb exists for our TR dashboards.
Thanks John...just the info I needed. I'll probably order one soon just to have it in the glovebox.
