There are 4 wires to the alternator which has an internal regulator:

1. BAT (Red) - main output
2. S (Red) - 12V supply continuous to regulator
3. L (Brown) - 12V Supply to regulator via 'Charge Indicator' bulb in Telltale Assembly (gages supply)
4. I (Blue) - 12V supply continuous to regulator (cooling fans supply)

With ignition ON and engine OFF all 4 wires need to have 12V to the alternator and the 'charge indicatot' light on the dash should be ON. What I have found is I am not getting power on the brown wire (L) and no telltale light. The 10A gage fuse is fine so the suspect is the 'Charge Indicator' bulb in the telltale assembly (above the radio?)

The problem I have is I cannot find such a bulb. Can anyone shed some light on this?

 

Some picture of my telltale panel above the radio which shows no bulb for battery charging:

 

I am looking for the 'battery charge problem' bulb that the 87 service manual talks about. Doesn't exist from what I can make out.

 

The battery charge problem bulb is would be part of the digital dash LCD screen.....when your voltage drops, a red light pops on and even if you have your switch set otherwise, the low voltage warning takes over and warns you.

 

I thought the charge light is supposed to come on every time the ignition is first switched ON.

 

wow, never seen that "overdrive engaged" sign !!!

 

It is on the cover plate but there are no bulbs to illuminate it. Same for the choke.

 

Those indicators aren't anything like my 87

My panel shows these messages: (left to right then top to bottom)

Door Ajar, Security, Low Tire Pressure, Hatch Ajar
Seat Belt, Service Engine Soon, Service LPTWS, Brake
Battery, blank, Low Coolant, Anti-Lock

The O/D engaged icon is just above the tachometer digital number display. It's a letter "D" with a box around it. There is also an upward pointing arrow that illuminates to indicate you should upshift. Nothing in the DIC at all about OD. And there is no "choke" icon in my car.

I have never seen a panel like yours. I wonder if this is from an earlier car (maybe 84??) or if it's for an export car?

If there is a too high or too low voltage condition, there is a battery icon at the bottom of the volts/coolant temp display. That will illuminate if there is a voltage problem. If volts are below 11.6v or above 16.5v, this icon will be illuminated. I think that is the one that the FSM is talking about.

The DIC has a "Battery" light and that should illuminate when the igniton switch is turned to the RUN position without the engine running.

As far as the bulbs themselves, my 87 owner's manual says all of the bulbs in the DIC are 194's. Bulbs in the instrument cluster are 882's.

 

That must be an export panel, I've never seen one like it. I know on some other GM models the "choke" light is also the charge light. Maybe that's what's going on.
What voltage are you getting with the engine running?

 

My 87 was an export to Japan. The choke light has no light socket / bulb behind it as shown in the image above. I also have an 84 and that doesn't have a charge light on the telltale panel.

My battery reads about 11.5 volts when engine stopped and running.

 

That's not a domestic (US) lens. Or Ecklers is using a wrong picture.

I don't have a good pic of the lens in my 87 as it's in the car but there is no "choke", no OD icon and there is a Low Tire Pressure (top row, 3rd position) and a Service LPTWS (2nd row 3rd position).

 

My 87 has the LPTWS indicators. There certainly would be differences on the panel depending on options. My 87 is a late production car and it's entirely possible that the 88 panel was used at that time. The lens in my car also has the battery icon in the lower left corner but it also has the battery icon in the selectable Volts part of the dash display. And it does work.

RPO UJ6 was an option for 87 but if it wasn't available until late in the model year, that could explain the change to the 88 panel.

But the "Choke" icon still doesn't make any sense for TPI cars? The ECM controlled cold idle operation with inputs from the coolant temp sensor and the MAF sensor. It's more like an 84 TB thing.

 

There is a battery symbol on your dash that lights red when the charging voltage is out of spec. The brown wire on the alternator grounds this wire to turn on the battery symbol. Engine not running, the brown wire will not have 12v on it because it is grounded. Also, the battery voltmeter on the dash reads low when the engine is not running and you shouldn't believe its reading.

 

My OD is at the tach, and the

 

My USA delivery '87 ( 86/345 build ) has exactly same panel

However; the '87 owners manual makes reference to the LTPWS warning lights ( pg 2 C-7 )

Mine did not have that option

 

I have confirmed that I do not have 12 V on the brown wire (with the 3 wire connector unplugged) when the ign is ON but engine OFF. I have also confirmed that I do not have a battery symbol or bulb in the telltale panel above the radio. It is possible a previous owner has put in the wrong telltale panel.

That explains why my alternator is not charging. I will see if I can trace the brown wire and get an ign switched 12V feed to it via a resistor (simulating a bulb).

 

FSM should show you what terminal on the DIC connector it goes to
Would look it up for you but I sold my '87 FSM to somebody........

 

That would be me!

The manual shows an 18 pin connector. The brown wire is terminal 15 and the pnk/blk ign feed is terminal 14. So all I need to do is connect a resistor between terminal 14 and 15 on the telltale panel.

 

Do any of your other DIC lights work.
Early cluster appears to have completely different inputs at connector.
Sent you a pic

 

Most of the other lights all seem to work.Thanks for the pic.