Many M816 Questions

[Guyfang]

No, not after market. It is the "New" light switch that the military bought. There are some smart people here who can tell you how it is SUPPOSED to work. Simp for one will know. Many others. I hated the darn things and liked the old three handled ones. If you look at the wire diagram, you can use a wire to test lights, at the plug. I THINK, but haven't looked in 10 years, but think pin A is power. You can jump from power to each circuit and get lights to com on, one at a time. I am sure the test procedure for the switch is in the books.

 

[Ajax MD]

I will NEVER understand why the military thinks the new switch is superior. It offers nothing ergonomically, over the original.

 

[98G]

I will NEVER understand why the military thinks the new switch is superior. It offers nothing ergonomically, over the original.

Unlike the original, the new one will burn your truck to the ground. I'd avoid it and find a 3 lever switch.

 

[Ajax MD]

Unlike the original, the new one will burn your truck to the ground. I'd avoid it and find a 3 lever switch.

I was just commenting. I don't own one of these switches.

 

[BillTWD]

Are the headlight connectors considered, "H4"? While looking for a headlight I found some H4 adapters. They look like the right ones.

 

[fasttruck]

Post 20: the pictured light switch was a replacement geniuses in TACOM dreamed up to replace the original lever operated switch. One drawback was you had to see it to figure out where it was set or change it. It was also somewhat unreliable and I am informed several electrical fires were attributed to these switches. So issue of the original lever operated switches resumed. If you found one on the floor it may have been replaced with an original swatch which was retained by the previous owner.

 

[BillTWD]

1.) Does anybody know what this thing is for? I found two of them in one of the bins on the back of the truck. It looks like a pipe clamp but it looks like the hooks for the other end of the chain are backwards.

2.) That stinking light switch - all it does is flash those little blue lights. None of the buttons do anything and the lights on the switch never stop blinking. I'm thinking maybe a short somewhere? Or the switch is bad? Improper ground?

3.) The taillights - are the taillights just those little rectangles (roughly 3/4" high by 3 1/2" long)? The bigger round(ish) lights above those come on as brake ights but they're not on as taillights (running lights) are they supposed to? If the taillights are just those little rectangles, it that street legal?

4.) Blinkers - how do they work?

 

[eric67camino]

1.) Does anybody know what this thing is for? I found two of them in one of the bins on the back of the truck. It looks like a pipe clamp but it looks like the hooks for the other end of the chain are backwards.

2.) That stinking light switch - all it does is flash those little blue lights. None of the buttons do anything and the lights on the switch never stop blinking. I'm thinking maybe a short somewhere? Or the switch is bad? Improper ground?

3.) The taillights - are the taillights just those little rectangles (roughly 3/4" high by 3 1/2" long)? The bigger round(ish) lights above those come on as brake ights but they're not on as taillights (running lights) are they supposed to? If the taillights are just those little rectangles, it that street legal?

4.) Blinkers - how do they work?

Those "things" are axle clamps for the tow bar. They wrap around the axle and the tow bar attaches to them.

 

[Guyfang]

When the light switch just blinks, its my understanding that its bad, Why dont you get an old three handle switch? THEN try and troubleshoot the light system.

 

[BillTWD]

Does anybody know how long of cable I should have on the crane hoist? I think it's 7/16" cable (could be wrong). I searched through the TMs and think I found a part number but couldn't find any specs/info.

 

[fasttruck]

Lights: All tactical vehicles have two independent lighting systems controlled by one switch so only one can be used at any time. The small lights at the bottom of the composite light are black out marker lights. There are two white lights on the front lamps and four red lights on the rear. There is also a small white light at the bottom in the rear which is the black out brake light. On older vehicles the black out brake light is a separate fixture. The blackout drive light is a single hooded fixture either in the grill or mounted on the left front fender. Blackout lights are a relic of WW2 are designed to make the vehicle harder to detect from the air. They are visible horizontally for some distance. The blackout lights are not street legal. They should not be lite in conjunction with the service lights. The theory nof blackout lights is explained in the "Wheeled Vehicle Drivers' Handbook" among other places.

Reference the light switch: when it is blinking have you tried selecting one of the functions ? I have little recent experience with these switches but I recall when you push one of the buttons ( ser drive for instance) the selected light will come on and the blinking stops.

The thingies with the chains are used to hook up a drawbar when the shackle points on the front bumper are not available as when damaged in an accident.

 

[fasttruck]

Reference post 31: If you cannot get all the lights to work by pushing the various buttons on the switch you need a new light switch. Get one with the levers, it is a direct interchange. I think the center button on the push button switch turns it on, then push the button for the lights you want. The instrument panel lights also go through this switch whether it is buttons or levers.

 

[Guyfang]

I looked in the TM's for the cable. The CABLE Assy, has a part number of: 10900237. That gets you the cable and cable end. The TM tells you to MAKE the cable from Bulk cable, part number of: 7600767. The tech spec's for the bulk cable are below. But I could not find the length of cable needed. Strange.

	DIAMETER	0 1/2 INCHES NOMINAL ROPE
	LAY METHOD	RIGHT REGULAR ALL LAYERS
	BREAKING STRENGTH	23000 POUNDS NOMINAL
	CORE CONSTRUCTION	FIBER
	PREFABRICATION FORM	PREFORMED
	MATERIAL	STEEL IMPROVED PLOW OVERALL
	MATERIAL DOCUMENT AND CLASSIFICATION	RR-W-410 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
	STYLE DESIGNATOR	6 X 19

 

[BillTWD]

OK

 

[BillTWD]

I looked in the TM's for the cable. The CABLE Assy, has a part number of: 10900237. That gets you the cable and cable end. The TM tells you to MAKE the cable from Bulk cable, part number of: 7600767. The tech spec's for the bulk cable are below. But I could not find the length of cable needed. Strange.

	DIAMETER	0 1/2 INCHES NOMINAL ROPE
	LAY METHOD	RIGHT REGULAR ALL LAYERS
	BREAKING STRENGTH	23000 POUNDS NOMINAL
	CORE CONSTRUCTION	FIBER
	PREFABRICATION FORM	PREFORMED
	MATERIAL	STEEL IMPROVED PLOW OVERALL
	MATERIAL DOCUMENT AND CLASSIFICATION	RR-W-410 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
	STYLE DESIGNATOR	6 X 19

That is the same part number that I found but I did not see those specs. Thank you. I had to use a cutting torch to get the old cable off. They had it wrapped around the bottom spool several times and bound so tight that they bent the control lever trying to do whatever they were trying to do. It took a couple of hours of cutting and hammering to get it out. I measured a piece of it with a caliper and it was shy of 1/2" so I assumed 7/16" although I suspected it might actually call for 1/2". As for length - I suspect that you don't want it too long (and obviously not too short). I noticed the bottom spool is grooved. Does that mean that we don't want overlapping wraps? I could see how the length might vary depending on whether we use a single pulley or a double pulley hook. Would we want to determine the length by rising and extending the boom to max with the hook touching the ground?

 

[Guyfang]

That is the same part number that I found but I did not see those specs. Thank you. I had to use a cutting torch to get the old cable off. They had it wrapped around the bottom spool several times and bound so tight that they bent the control lever trying to do whatever they were trying to do. It took a couple of hours of cutting and hammering to get it out. I measured a piece of it with a caliper and it was shy of 1/2" so I assumed 7/16" although I suspected it might actually call for 1/2". As for length - I suspect that you don't want it too long (and obviously not too short). I noticed the bottom spool is grooved. Does that mean that we don't want overlapping wraps? I could see how the length might vary depending on whether we use a single pulley or a double pulley hook. Would we want to determine the length by rising and extending the boom to max with the hook touching the ground?

I cheat. I had someone look it up in the Army for me. The tech info is not in the TM's. I seem to remember doing the cable one time about 40 years ago. And indeed we raised the boom up and roiled up cable till the drum was full and the cabe was cut just above the ground. I do remember it was a super PITA.

 

[BillTWD]

Reference post 31: If you cannot get all the lights to work by pushing the various buttons on the switch you need a new light switch. Get one with the levers, it is a direct interchange. I think the center button on the push button switch turns it on, then push the button for the lights you want. The instrument panel lights also go through this switch whether it is buttons or levers.

That was a small treasure chest full of useful information. Thank you very much, sincerely. I have attached a picture of one of the taillights on my M816. The big half-round lens on the top - is that multi-function (running/taillights, brakes & blinkers)? I would think that the smaller lights on the sides are side markers and possibly blinkers too?

 

[Guyfang]

That was a small treasure chest full of useful information. Thank you very much, sincerely. I have attached a picture of one of the taillights on my M816. The big half-round lens on the top - is that multi-function (running/taillights, brakes & blinkers)? (correct) I would think that the smaller lights on the sides are side markers and possibly blinkers too? (No, just marker lights)

 

[fasttruck]

Reference post 37: from top to bottom: service taillight. 2 bulbs, smaller one is for tail light, larger 2 filament bulb is stoplight/turn signal. Army uses the turn signal circuit in tandem to operate brake lights. Unlike a commercial truck, there is no separate brake light circuit. Next is blackout marker light which on a rearward facing light has 4 red apertures and depending on how far away you are your eyes will resolve 1, 2, or 4 individual lights. Bottom light is blackout brake light which is white when lit. If you are in convoy and you see 8 red marker lights with 2 white lights under them, brace yourself for the collision. The military light switch does not allow blackout and service lights to be displayed at the same time. Front composite light has an amber lens on top which is the parking light/ turn signal and a white blackout marker light beneath it. The operators' manual; has information in it about lights and it is also discussed in the Wheel Vehicle Driver's Handbook. The Wheeled Vehicle Drivers' Handbook is FM 21-305.

 

[BillTWD]

Reference post 37: from top to bottom: service taillight. 2 bulbs, smaller one is for tail light, larger 2 filament bulb is stoplight/turn signal. Army uses the turn signal circuit in tandem to operate brake lights. Unlike a commercial truck, there is no separate brake light circuit. Next is blackout marker light which on a rearward facing light has 4 red apertures and depending on how far away you are your eyes will resolve 1, 2, or 4 individual lights. Bottom light is blackout brake light which is white when lit. If you are in convoy and you see 8 red marker lights with 2 white lights under them, brace yourself for the collision. The military light switch does not allow blackout and service lights to be displayed at the same time. Front composite light has an amber lens on top which is the parking light/ turn signal and a white blackout marker light beneath it. The operators' manual; has information in it about lights and it is also discussed in the Wheel Vehicle Driver's Handbook. The Wheeled Vehicle Drivers' Handbook is FM 21-305.

Thank you. I have ordered a new 3-lever light switch. Hopefully that will help put it all together. Other than the driver's side rear lights, which have obviously broken and separated wires, I might even get lucky with the other stuff working. I guess I'll find out when the switch arrives. Happy Thanksgiving.