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All: Like most my posts, this intended to share information. I am in the process of upgrading both interior and exterior lighting on my '84 C4 (manufactured 10/83), so using this chart is much easier than yanking bulbs to find a part number. This is a jpeg of page 8B-24 from the "1984 Corvette Shop Manual": To convert Candle Power to Lumens, multiply by 12.57. Ex: 1156 bulb's 32 candle power X 12.57 = 402.24 Lumens. The 1156 is marketed as a 400 Lumen bulb.
All: Like most my posts, this intended to share information. I am in the process of upgrading both interior and exterior lighting on my '84 C4 (manufactured 10/83), so using this chart is much easier than yanking bulbs to find a part number. This is a jpeg of page 8B-24 from the "1984 Corvette Shop Manual": To convert Candle Power to Lumens, multiply by 12.57. Ex: 1156 bulb's 32 candle power X 12.57 = 402.24 Lumens. The 1156 is marketed as a 400 Lumen bulb.
Good job. Handy. cross- reference/ conversion.
cheat sheet.!
Lil bias.. ha ha. Hint..
It's official. Can you convert the later models.
For the members.
LEDs save alot of power. Much lower operating temps. Way better. Especially 4.8k - 5k perfect Kelvin color. Like HD.
Only down side. Vulnerable to water saturation. and spiked voltage
"Can you convert the later models.
For the members.
LEDs save alot of power. Much lower operating temps. Way better. Especially 4.8k - 5k perfect Kelvin color. Like HD.
Only down side. Vulnerable to water saturation. and spiked voltage."
Can I convert the later models? No...I just have the GM shop manual and the chassis electrical supplement manual for the '84. I think I have the shop manual for my '98 C5. It is very likely that the following years of C4's have the same bulbs as my '83'. When I removed the passenger door courtesy / "map" bulb, the plastic housing was burned and melted obviously due the incandescent 211-2 bulb (the chart indicates that bulb is a 212-2 but the one I removed was a 211-2). Applying 12.7Vdc to the 211-2, I measured 600ma which is 7.68 Watts. I haven't removed the driver's side bulb so it might be a 212-2. There's no question that the LED is superior to incandescent bulbs in terms of more lumens at substantially less power consumption.
Good news...The results are in with the LED interior lighting swap. I replaced the foot well, door "map" light and the cargo incandescent bulbs with LEDs. The mission was twofold, reduce current through the delay light timer's output transistor while increasing the brightness of the lighting. I measured 750ma with the LEDs and 4.5 amps with the stock incandescent bulbs. Not only is the current dramatically reduced but the brightness of the LEDs is orders of magnitude brighter. Next up will be replacing the exterior side lights. I replaced the delay timer transistor with one rated at 10A, collector to emitter. That delay timer transistor failed in both of my '84 C4s.
Good news...The results are in with the LED interior lighting swap. I replaced the foot well, door "map" light and the cargo incandescent bulbs with LEDs. The mission was twofold, reduce current through the delay light timer's output transistor while increasing the brightness of the lighting. I measured 750ma with the LEDs and 4.5 amps with the stock incandescent bulbs. Not only is the current dramatically reduced but the brightness of the LEDs is orders of magnitude brighter. Next up will be replacing the exterior side lights. I replaced the delay timer transistor with one rated at 10A, collector to emitter. That delay timer transistor failed in both of my '84 C4s.
I decided against LEDs for side running lights. The LED 194 equivalents did not illuminate out the lens but rather side to side inside the lens. Sure, light does get out the lens but not nearly as much as the incandescent 194 bulbs which are fundamentally omnidirectional. I have two options: (1) search for LEDs that are configured to beam light into the lens or (2) just stay with the standard 194 bulbs. I opted to continue to use the 194s rather than spending more bucks for omnidirectional LEDs. Reduce current was not an issue like it was for the interior lighting delay timer so the incandescent 194 bulbs are OK.
I replaced the delay timer transistor with one rated at 10A, collector to emitter. That delay timer transistor failed in both of my '84 C4s.
Could you go into more detail? Mine gets quite warm even with LEDs. Passenger side footwell died this week, checking wires shows no power, LED still works with direct power
Could you go into more detail? Mine gets quite warm even with LEDs. Passenger side footwell died this week, checking wires shows no power, LED still works with direct power
(1) I would expect the transistor to be warmer than ambient temperature but not 'hot' to the point of failure. There is likely a current difference between your LEDs and mine. I did not measure temperature, just the total current flowing through the transistor.
(2) Checking the wiring diagram (jpgs from the Electrical Troubleshooting Shop Manual), the Door Courtesy lamps are the "Foot Well Lamps" from the shop manual. There is a wording difference between this manual and the Shop Manual. The RH Foot Well lamps are powered through connector pins C501 and C332 (Orange wire in jpg, page 8A-53, bottom pix). I would locate that connector and check for continuity. The delay timer output transistor's base current turns the transistor on, so the bulbs are ON. Page 8A-52 Electrical Troubleshooting Shop Manual Supplement 1984 Corvette.
Page 8A-53
I thought you kept the 194 front side marker bulbs because LED in that position don't operate properly.
In one polarity, the side markers will illuminate with park lights on. Will alternate flash turn signal with park lights on. But will NOT flash turn signal with park lights off.
The other polarity, The side markers do not illuminate with park lights on. Will alternate flash turn signal with park lights on. Will flash turn signal with park lights off.
The LEDs worked OK in place of the incandescent bulb; I wasn't satisfied with their light output. I did not check for turn signal function. The pix is from the Electrical Troubleshooting Shop Manual, page 8A-43., it should help figuring out the problem you describe.
I have no difficulty figuring out electrical circuits. I have 6 years of FSMs and an 84 wiring .pdf as well. But thanks.
In your schematic above, note that the front marker is connected between the park light circuit and the turn signal circuit. Either wire can be +12V; either wire can be at Ground potential when the circuit is not powered. If one wire is powered and the other is not, the side marker is illuminated. If both wires are powered, or at Ground potential, the side marker is off.
Put an LED bulb in the front side marker position and the side marker will no longer function the way it is intended to. LEDs only conduct in one polarity. The front side marker has to illuminate in both polarities. LEDs can't.
Regardless of how they are wired, when the LED was on, there wasn't enough lumens coming through the red lens that I was willing to replace the original 194 bulb.
I mentioned in another post somewhere in this forum, when it comes to car wiring, forget everything you know. If the manufacturers can save one foot of wiring by shortcuts, then multiply by millions of vehicles manufactured that converts into very big bucks saved.
09-29-2022, 06:48 AM
'84 C4 bulb chart
