Ok been gone for a while , on the road , checked the fuel preasure between 25 and 34 no problem there , left it with my mechanic ,, Here's what's going on . The1st pcm was rebuilt and replaced before the wire harness .. The wire harness had 2 wires that were melted a bit causing a short to the selinoid . This also fried the rebuilt Pcm .. could not be rebuilt again .. Now as it is a 98 the pcms are rare so much so that it is a real problem ,,called all the rebuilders all the parts houses found 1 at 950$ after 2 weeks found a new one on a shelve for 500$ . This one was not programmed at all .. when received my machanic got the program from dodge some stuff worked tack and speedometer didn't . Also transmission didn't !!!!yesterday the pcm had to be it taken in to dodge to get a hard flash from there computer to fix this this . ,, Turns out the 98 has several controls the 93 thru 97 does not . and they only made this pcm for 6 months .. The pcm can shut down this truck and tied up the fuel selinoid won't help .. . So as of now this is all I know .will up date as it goes . I can say one thing seems that the short in the wire harness is not unusual from 98 on ..

 

First off, if it really is a 12 valve, the PCM cannot shut the truck down if the lever is tied.

There are some wiring differences, but the only electrical difference is in the gauge cluster which switched to the digital odometer/ data bus style.

You are right though, 98 is a mess wiring wise with the mid year introduction of the 24Valve, there are subtle wiring differences between the 2 and not all are well documented. That is why I have always stuck with the 97 MY trucks.

 

hmmm all I know is when it was wired up the truck still died and would not start . mechanic it is at now ,,says the pcm can shut this one off .. it is a 12 valve pcm went into dodge local dealer for a patch for the auto tranny back in truck now transmission still not working . thought I'd done my research on trucks to buy when I got this Cummings 12v . wish I would have known they made changes from the 93to97s . this is turning into a small pain in the rear . Thankfully I have 3 Isuzus to use hitting the road again next week would have been nice to drive a truck that would go faster then 58mph .

 

Patdaly said it, PCM has no control over engine running with the lever tied up. Mechanical injection pump and mechanical supply pump stock. PCM controls charging, a/c, gauges etc.

If it is still cutting out, it is either the linkage not connected properly on FSS (woodruff key) or a problem with the pump itself. Lots of people say these p7100s are indestructible but I have seen a few (including mine) go before 250k miles with odd behavior.