Delcotron 12SI problem

[pontiacgp]

Mark, I put in aftermarket gauges so the red light that was used for resistance is gone. I took the brown wire and put a resister in the wire and and attached that to a switched power feed and it charges perfectly. The package came with two resisters so I have one here doing nothing but collecting dust. I can send it to you if you'd like or if you want to pick one up it's a 85R 3W 5% resistor

 

[Bonnewagon]

Thank's for the offer Steve. If that's really the problem I have plenty of resistors lying around. What I really want is to get it working with stock components, rather than a band-aid. The guy in the article said basically the same thing concerning Jeeps and offered this fix-" What you want is a Vishay-Dale RH-50 series power resistor in 15-ohms. It is an aluminum heat sink encased environmentally sealed power resistor that can be bulkhead attached and your wiring soldered and heat shrink insulated to the termination lugs. Operating Temperature range is -55 C to + 250 C good for anywhere on the planet earth. The model number would be RH0505015R00F. http://www.vishay.com/docs/30201/30201.pdf
RH-50
RH-50

Quick, simple and fairly cheap, less than $10 dollars for one shipped to your door. A distributor called electrospec should have some in stock... http://www.electrospec.com/account/rfqcart.asp "

 

[Bonnewagon]

Well, it looks like both Jack and Steve hit it dead on. I caused my own problem by switching to the '78 gauges and thinking all would be well by doing nothing more. Here is what I found out. Both before '78 and beyond, if you had idiot lights, the ignition "on" circuit fed the indicator bulb which was in the field wiring circuit and provided battery voltage for the alternator's rotor field to initiate charging until the alternator's output was enough to sustain itself. As soon as alternator output equaled battery voltage, the bulb saw equal voltage on both sides and it went out. When I switched to GP gauges years ago, the GP voltage gauge ('86 I think) included an indicator bulb, which was wired separately from the gauge itself, and did the same job as before. Now in '83, which is what my car is, if you had factory gauges, the choke heater relay was in the field circuit and did the job, and if the alternator failed the choke warning indicator came on. But my car came with idiot lights, and my current dash has no choke indicator, so now what? By swapping in a '78 voltage gauge, it had no indicator bulb, thus no field circuity, so what did they do in '78? They used a 24 gauge 10 ohm resistor wire in the field circuit! Props to the '78 Pontiac factory manual for that info. So to solve my problem I must check and see exactly where my field wire is on my current dash cluster and either run it to ignition "on" with a resistor, or add an indicator bulb to my '78 gauge wired to the field circuit. I'm thinking the gauge pods are similar if not the same and the cavity for the bulb is probably here. If not I have later pods to use. I can maybe add the indicator red lens from a later gauge to my '78 gauge. Oh well, it looks like I'll be opening up the dash again. Thank's Jack and Steve, you were both right!

 

[Longroof79]

Mark,
Glad that we were able to help. When I first noticed that my alternator wasn't charging, I tried using the green oil pressure sensor indicator lead, which is also a switched +12 volt source, connected that to the "L" connection on the alternator. I then noticed that it began to charge.
I'm sure the choke circuit could also be used for the same purpose.

 

[pontiacgp]

Well, it looks like both Jack and Steve hit it dead on.

actually when I was setting up my aftermarket gauges Jack gave me all the info about the resistor so I was just relaying what Jack had told me..some of old guys still have a memory that works on occasion...

 

[Longroof79]

some of us old guys still have a memory that works on occasion...

:? :lol:
as the old adage goes, "Use it or lose it". :lol:

 

[Bonnewagon]

So here's what happened- I pulled the gauge pod out and compared it to another and, wowsers- no hole for the indicator light! But the printed circuit and everything else was identical so the field wire went- nowhere. Steve, you remember the metric gauges you sent me a while ago? I used the pod they came in and swapped my silver gauges over to it. Then I figured, why put the bulb in and not have the telltale red dot? So I drilled a tiny hole in the proper place under the "volts" logo and removed the red plastic lens from your volts gauge and placed it behind my gauge. Now the field wire goes to a bulb and switched ignition like it should, and when I tested it, the bulb showed 5 ohms resistance, how about that. Put it all back into the dash and turned the ignition key to 'run' and the red dot lit. Then I started it and the volts jumped immediately. FIXED! And for all those that want to say, "Hey ********-you mean you never tested the alt field terminal brown wire for voltage before driving yourself crazy?" All I can say is- DOH! The left pod is Steve's '80-something, the right is my '78- no gen bulb.

 

[pontiacgp]

hmmmmm..... the circuit board is the same on both but no provision for the light on the 78. I wonder how the 78 worked

 

[Bonnewagon]

Yeah, funny, right? But don't forget, '78 was the new downsized A/G body and this was a new dash design. The silver gauges were for '78 only, with the 10 ohm resistor wire. So unless you look at one, you'd never know. Later they went with the design with the bulb we are familiar with.

 

[Longroof79]

Great detective work, Mark.
I'm glad you got to fix it the right way. So you ended up using the later type gauge pod with the provision for the gen. light?