What is the difference between blackout stop lamp pin 23
and service stop lamp pin 22?
Also, what is the new Federal reg regarding stop lamp area?
Does the OEM left stop lamp qualify for a driver, or does one really need the Gamma Goat lenses?
One more question. For a theoretical motor pool vehicle, would a replacement single connection light switch be applicable for an early M38?
1-Service stop is the red lamp on the left. BO stop is the BO lamp on the right. Weather the stop signal from the brake switch goes to 22 or 23 depends on the position of the main switch.
2-The military generally upgraded all the M series trucks to the single plug switch. Granted a few slipped through the cracks but most were upgraded out of necessity or the need for commonality of parts. All the military main light switches including the modern push button found in most m series trucks today use the same large plug. When replacing the two plug switch in a truck with a two plug harness you must move the wires from the small plug to their appropriate pins in the large plug.
3-You need to look at your state's DMV laws as well as federal. Most grandfather in old single tail lamp antiques and no turn signal antiques. The stock service stop lens on the left is adequate in most states. If I were building a motor pool class resto of an old 45 MPH jeep and wanted to drive it a lot in modern traffic and did not want to get hit in the arse a lot I would use at least two of the left red units or two gamagoat lenses. Since most idiots on todays road have no idea what any hand signal means I would not run in heavy traffic without bright red stop/tails and turn signals! _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: May 30, 2014 Posts: 3452 Location: Texas Hill Country
Posted: Mon Aug 04, 2014 10:09 am Post subject:
Thanks for the replies Wes.
I will plan on two of the left light units and start looking for a single plug light switch. Is there a way to readily identify the rebuildable earlier single plug switches versus the throwaways?
Pulled the gauge cluster this morning. Nothing original except for the speedo and it is fried and was not hooked up. No semblance of original wiring, and the only working gauge was the oil pressure with aftermarket plastic oil line.
Oh, except for the gauge lamps. I figured out how to pull them apart. Other than the wire being toast, and paint on the glass, and the rubber being crispy in a couple of places, they seem serviceable.
I would like to rebuild the cluster as close to original as possible, but temporarily utilize the 12 volts the vehicle has been converted to. I know it is probably more work, but it looks like two of the gauges are not powered, unless I am missing something. The speedometer appears to be wholly mechanical, and I can utilize the oil gauge with oil line for the time being. The 12 volt replacement units are fairly cheap compared to 24 volts, and I think I can rationalize using them until I get to spending the real money converting the big ticket items. By then I suspect I'll think the 24 volt gauges are cheap!
I saw somewhere where an AC Delco voltage or Ammeter gauge was being sold for 6, 12 or 24 volt depending on the resistors, which are included.
One more question. It looks like the light wiring beginning with the voltage into the light switch from the dash connection could be used for 12 or 24 volt as drawn, if one just changes the lamps. Does that sound right?
The 2nd Bendix style light switch with two machined areas for plugs but only one plug is the only rebuildable light switch. All the rest including the modern pushbutton are throw aways. You'll hear from guys that have bent and cut throw aways apart and managed to clean contacts and force them back together but a clump of switch boards and wires springing loose behind the dash a starting an electrical fire is one way to turn yourself off quick on the cost of operating old vehicles. Also you can make the Bendix 1st style two plug work in any one plug jeep with a few minor modifications.
Chapter 5 of this manual is loaded in PDF on our downloads page for the plug repairs.
If you now have 12 volts then most likely you have an alternator. Either way a voltmeter is a better choice to monitor the condtion of your electrical system and the easiest to install. All four of the original system gauges were 24 VDC electrical used with 24 VDC senders. mising them with 12 volt will yield incorrect readings. My advice is to use mechanical gauges as much as possible. Water temp, oil pressure, speedo and use a 12 Volt voltmeter for 12 volt system and 24 volt volt meter for 24V systems. Your fuel gauging system was originally 24V sender and gauge. Again mix and match will give you errors.
On using 24V military light switches with 12 volt systems the early Bendix switches utilized an external circuit breaker for protection that was mounted on the M38's dash battery box. The later one plugs utilize and internal auto-reset circuit breaker that is rated for 24 volt lighting. Depending on quanity and amp rating of your lamps you may end up getting nuisance trips with the internal circuit breakers. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Wes, do you have any pictures of the wiring harness running from the front to the rear under the tub? Anyone know where I can find the fender blackout wire clips?
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