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As mentioned in Part One, it’s helpfulto think of a vehicle’s fuel and ignitionsystems as chains of components, eachchain having a beginning and an endand all their links vital in between; andwhile a fuel system begins at the tankand ends at the carburetor, an ignitionsystem begins at the battery and ends atthe spark plugs.this occurs, will stubbornly go oncranking the engine until the battery isdead. Even if one doesn’t believe thatsome vehicles have nasty personalities,they should still be familiar enoughwith their HMV’s characteristics torealize that if it has faithfully fired-upevery morning with three cranks of thestarter, and then one morning it refusesto start, it’s very likely that something iswrong. And, as mentioned in Part One,if you are out in the wilds or far from home, treat your batterypower as if it was money—save all you can—because once it’sgone it’s usually hard to replace.Since we’re dealing with the most common roadable HMVs,there are two basic types of ignition systems to diagnose and repair.The first type is used on virtually all pre M-series vehiclesdating back though and before WWII. These systems are thesame types used on civilian cars and trucks of the period, andare the simplest to troubleshoot and fix. Their voltage is usuallyeither 6 or 12, and just about all of their tune-up parts—points,spark-plugs, condenser, rotor, distributor cap and ignition coil—can often be found at well-stocked auto or truck supply houses,while complete distributors may still be located at older wrecking-yards,especially those in rural areas.The second type is the M-series 24-volt waterproof ignitionsystem common to HMVs such as the M38, M38A1, M151,M37, M715, M2ll and early M35s. This system is more difficultto diagnose and repair in the field because both the ignitioncoil and distributor are combined in one waterproof unit... oftencalled the Igniter. Field testing such a system presents moreof a challenge because the Igniter must be fully assembled tofunction. Trouble-shooting these systems is often a matter of replacingdoubtful parts until the engine starts again. Also considerthat just about every component of an M-series 24-volt ignitionsystem is Government Issue and, unlike the older WWII systems,there are almost no civilian counterparts... except sometimes thepoints, condenser and/or rotor. It should therefore be apparentwhy spare parts need to be carried; tune-up parts (at least) forshort trips, and major components such as a spare starter, generatorand voltage regulator when traveling far from home or intothe wilds.There is a third type of ignition system one may sometimesencounter on common HMVs: this is when someone has cobbledtogether a mutant system using both civilian and military M-series components. While most dedicated HMV owners wouldhave changed these systems back to original, there may comea time when one is stranded somewhere and will have to createa mutant system to get their vehicle going again. More on suchsystems later.START WITH THE OBVIOUSLet’s go back to Part One of this piece where we were cruisingalong a moonlit highway and the vehicle’s engine quit. Using theprocedures covered in that first article installment, we have determinedthat the problem is not in the fuelsystem. As also mentioned in Part One,we know that it’s helpful to think of ourvehicle’s fuel and ignition systems asThe ignition system used on mostcommon U.S. M-series (post WWII) HMVsis the 24-volt, waterproof type commonto vehicles such as the M38, M38A1,M151, M37, M715, M2ll and early M35s.This system is more difficult to diagnoseand repair in the field because both theignition coil and distributor are combinedin one waterproof unit...often calledthe Igniter. Field testing such a systempresents more of a challenge becausethe Igniter must be fully assembled tofunction.Military Vehicles Magazine June 2013 35