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Old 12-31-2018, 01:40 PM   #1
Gregski
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What are the warning lights in the Speedo on a '78 and up?

I lost my orange/red see-through plastic lens that goes behind the speedo on a 1978 gauge cluster and would like to remember what those two warning lights were for? On the Tach side I have a Fasten Belts light and a Brake warning light. I am building my own custom gauges and want to have the corresponding idiot lights for all those. Can you help?
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Old 12-31-2018, 02:21 PM   #2
hatzie
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Re: What are the warning lights in the Speedo on a '78 and up?

4WD-Lock and ???
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Old 12-31-2018, 04:09 PM   #3
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Re: What are the warning lights in the Speedo on a '78 and up?

Choke is the other one I believe.
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Old 12-31-2018, 08:25 PM   #4
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Re: What are the warning lights in the Speedo on a '78 and up?

Thank you, I don't think I need either. And I knew as soon as I post this I would find that darn thing, and yup here it is.
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Old 01-14-2019, 05:58 PM   #5
wahl4m
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Re: What are the warning lights in the Speedo on a '78 and up?

the 2 wires from the transfer case -signal this 4wd lite ????? thanks for any info !
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Old 01-14-2019, 06:08 PM   #6
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Re: What are the warning lights in the Speedo on a '78 and up?

Quote:
Originally Posted by wahl4m View Post
the 2 wires from the transfer case -signal this 4wd lite ????? thanks for any info !
Look at the wiring diagrams. One leg of the 4WD lamp is direct from either circuit 39 or 150 in the instrument cluster plug...
I can't remember which off the top of my head. CRS

The switched leg, be it either the Hot or Ground, to the 4WD lamp runs through the transfer case switch. Again the wiring diagrams will tell everything you need to know.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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Old 01-14-2019, 06:12 PM   #7
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Re: What are the warning lights in the Speedo on a '78 and up?

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Thank you, I don't think I need either. And I knew as soon as I post this I would find that darn thing, and yup here it is.
Later trucks had CHOKE lights that were married into the switched regulator wire on the alternator. 74 didn't originally have electric choke wiring... IIRC it only had a BRAKE lamp on the gauge clusters, in the bottom of the tach or the lower left gauge slot, and that was it.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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Old 01-14-2019, 06:17 PM   #8
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Re: What are the warning lights in the Speedo on a '78 and up?

im trying to get this 81 k-30 -with a 87 cab finished up-got several wire problems ! [SORRY ABOUT HIJACKING THIS MESSAGE }this 2 prong plug runs fron transfer case up through cab JUST CANT SEEM TO FIND ATTACHING PLUG &WIRES FROM DASH -NEED TO LOOK AGAIN?? ALSO SEEM TO HAVE HORN HONK -WHEN I CLICK WIPERS ON HIGH ?? WIRING PROBLEMS ARE
FUNNNNNN
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Old 01-14-2019, 06:21 PM   #9
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Re: What are the warning lights in the Speedo on a '78 and up?

Quote:
Originally Posted by wahl4m View Post
im trying to get this 81 k-30 -with a 87 cab finished up-got several wire problems ! [SORRY ABOUT HIJACKING THIS MESSAGE }this 2 prong plug runs fron transfer case up through cab JUST CANT SEEM TO FIND ATTACHING PLUG &WIRES FROM DASH -NEED TO LOOK AGAIN?? ALSO SEEM TO HAVE HORN HONK -WHEN I CLICK WIPERS ON HIGH ?? WIRING PROBLEMS ARE
FUNNNNNN
Check the dash grounds. They're right above the e-brake pedal.
Won't cure everything but it'll help a bunch.
__________________
1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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Old 01-15-2019, 11:47 AM   #10
kipps
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Re: What are the warning lights in the Speedo on a '78 and up?

The horn is on the wiper/washer switch plug. So the wires are in close proximity at the steering column.

The horn relay, hazard flasher, and door/ignition buzzer are on the "convenience center" in GM's terms. Basically a small steel bracket that holds all three items and a pile of wires. Look for that unit somewhere down low in the dash area, and check for current at the horn relay. Then trace it back up to the wiper switch plug. If no problems between the relay and the switch, suspect the wiper switch.
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Old 01-15-2019, 12:15 PM   #11
hatzie
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Re: What are the warning lights in the Speedo on a '78 and up?

Quote:
Originally Posted by kipps View Post
The horn is on the wiper/washer switch plug. So the wires are in close proximity at the steering column.

The horn relay, hazard flasher, and door/ignition buzzer are on the "convenience center" in GM's terms. Basically a small steel bracket that holds all three items and a pile of wires. Look for that unit somewhere down low in the dash area, and check for current at the horn relay. Then trace it back up to the wiper switch plug. If no problems between the relay and the switch, suspect the wiper switch.
NO! The horn trigger wire is separate from the wiper wiring til it enters the cab harness.

Backfeeding from bad grounds causes all kinds of odd operational issues. Til the grounds are known to be good you will have a devil of a time finding any other issues. You could have damaged wiring or switches but the ground(s) need to be good to troubleshoot them.

The horn trigger from the button is in the Harmonica plug on the column along with the turnsignals/key-inserted/brake-lamp wires.

The wipers are either off the dash switch (pre 83ish) or, on 84 & later cabs with column wiper switches, plugged on the bottom third of the column. The wiper/washer plug position in the picture below may be on the base or side of the column tube on some models instead of on top but it's near where this drawing shows it.

From the 1991 Upfitters guide... should also be on PDF page 388 of the 1991 wiring diagrams. Applies to 84-91 CK/RV squares but the 1990 & 1990 RV wiring diagrams and upfitter guides are the only place to find wiring plug locations drawn in this manner. Thankfully GM didn't change a lot of these kind of routing and switch locations so it makes it easier to track down locations on the earlier models as well... they did change some but this is a good jumping off point.
C210 is the Headlamp Dimmer
C241 is the Wiper/Washer
C207 is the Ignition Switch
C212 is the Turn-Signal Harmonica plug (Turn/Hazard/Brake/Horn/Key-Inserted)
S206 is the driver side dash harness.

__________________
1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.

Last edited by hatzie; 01-15-2019 at 12:27 PM.
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Old 01-15-2019, 01:29 PM   #12
kipps
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Re: What are the warning lights in the Speedo on a '78 and up?

Quote:
Originally Posted by hatzie View Post
NO! The horn trigger wire is separate from the wiper wiring til it enters the cab harness.
Thanks for setting that straight. I was looking at too many diagrams and mixed up the wiper and turn signal plugs.

Thanks also for that pic.
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Old 01-21-2019, 06:03 PM   #13
wahl4m
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Re: What are the warning lights in the Speedo on a '78 and up?

WELL THANKS GUYS !!! now i need to get under the dash & ck everything! i just bought the tilt column off e-bay -looks nice BUT HOPE IT WAS NOT A BAD BUY -PfOBLEMS ?? the chassis was a 81-82 & cab is a 87-88 square - we did change front harness to a 86-87 loom !ckd grounds & everthing looks -hooked up ? anyway i will ck it again --
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