95 dodge ram 2500

Check the voltage at BOTH batteries while cranking. Put the meter probes right on the battery posts, not on the pinch terminals. See if they both read the same. Report back.

Al

Don't know if you checked the cable lug at the starter. Anyway, there is a rubber boot to keep all the crap off the connection, it has a drain hole that get's plugged with crap and corrosion set's in.

Roy

How does that make the voltage drop to 8? Do you think he measured it at the starter bolt? Could have I guess... Bet that starter terminal gets hot plenty fast when this happens:)

Al

Another thing I would do at this stage is to get or borrow a clamp on current meter to see how much power is going were during glow plug preheat and cranking. Also (and this one is a must do) put a voltmeter between each postive battery terminal when cranking and record reading and then between the starter and each postive battery terminal and record those reading to. (this will tell us how much voltage drop or current loss there may be and also if batteries are both carrng the load. Do this and let me see your numbers.