Possible to have 2 different alternators? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kensousa · 10-31-2022, 03:48 PM

'71 C10 short/fleet.
We have reason to believe it was a government issue truck due to a metal plate inside the glove box with a government serial / issue number.

The first picture is of two gizmos that are on the engine bay firewall, driver's side just above the bulkhead connectors. I can't find them referenced on any of the schematics that I've seen.

Second picture is an extra connector that I have and looks to me like a later model alternator connector? Those wires appear to originate in the two gizmos discussed above.

And third picture, I already have the stock alternator installed with the factory external voltage regulator.

Has anyone seen this before?

Southcity · 10-31-2022, 05:36 PM

I have not personally seen it but have heard of it on trucks of this time for fleet vehicles (i.e. electricians, welders) tow trucks (wreckers), emergency vehicles, etc., to help power auxiliary equipment.

**HO455** · 10-31-2022, 05:43 PM

I believe your looking at parts of the transmission spark control system that came on 71's. See link..
It may have only installed on trucks sold in California but I don't know that for a fact.

http://67-72chevytrucks.com/vboard/s...d.php?t=750604

**'68OrangeSunshine** · 10-31-2022, 10:42 PM

HO455 is right, the spaced connectors in pic 1 are for the TCS. An obsolete emissions control device that's best bypassed.
The connector shown in pic 2 is for the next generation alternator. Possibly used in tandem with the stock alternator to generate 24 Volts which is the power for military radios and other equipment.
Pic 3 is the stock '71 alternator used with an external voltage regulator.

10-31-2022, 03:48 PM	#1
kensousa Registered User Join Date: Jun 2011 Location: Inwood, WV Posts: 41	Possible to have 2 different alternators? '71 C10 short/fleet. We have reason to believe it was a government issue truck due to a metal plate inside the glove box with a government serial / issue number. The first picture is of two gizmos that are on the engine bay firewall, driver's side just above the bulkhead connectors. I can't find them referenced on any of the schematics that I've seen. Second picture is an extra connector that I have and looks to me like a later model alternator connector? Those wires appear to originate in the two gizmos discussed above. And third picture, I already have the stock alternator installed with the factory external voltage regulator. Has anyone seen this before? Attached Images

10-31-2022, 05:36 PM	#2
Southcity Registered User Join Date: Aug 2007 Location: Redwood City, CA Posts: 1,177	Re: Possible to have 2 different alternators? I have not personally seen it but have heard of it on trucks of this time for fleet vehicles (i.e. electricians, welders) tow trucks (wreckers), emergency vehicles, etc., to help power auxiliary equipment. __________________ 66 GMC Suburban Custom 66 Chevy K10 Suburban

10-31-2022, 05:43 PM	#3
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,350	Re: Possible to have 2 different alternators? I believe your looking at parts of the transmission spark control system that came on 71's. See link.. It may have only installed on trucks sold in California but I don't know that for a fact. http://67-72chevytrucks.com/vboard/s...d.php?t=750604 __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

10-31-2022, 10:42 PM	#4
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,502	Re: Possible to have 2 different alternators? HO455 is right, the spaced connectors in pic 1 are for the TCS. An obsolete emissions control device that's best bypassed. The connector shown in pic 2 is for the next generation alternator. Possibly used in tandem with the stock alternator to generate 24 Volts which is the power for military radios and other equipment. Pic 3 is the stock '71 alternator used with an external voltage regulator. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.



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