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Old 07-05-2015, 06:01 PM   #1
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Cummins Wiring Interface

I'm an authentic Chevy Guy, I have two, a 52 (since 1970) and a 73 K20 Camper Special. However, I have a project in the works for which I need some help; I'm not a real "strong" electrical person. My project is a 1948 Dodge COE on a 1977 Dodge M500 motorhome chassis and powered by a 1996Cummins 5.9 diesel. The mechanicals are easy enough but I've got to start coming up with an electrical interface. The engine has the wiring harness for the stock engine/transmission interface; there is no wiring or gauges in the cab, I'm starting from scratch. I've searched both the "electrical" and "diesel conversions" forums and not found good clear information on how to tie this engine into aftermarket gauges and what additional gauges might be required; I have read several opinions about preferred harness manufacturers. I'd appreciate some solid info on what you guys that have done this conversion in you Chevys have done, Thanks in advance. Jim
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Old 07-05-2015, 08:40 PM   #2
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Re: Cummins Wiring Interface

The 96 motor is a 12 valve "P" pump right? What trans is behind the motor?
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Old 07-08-2015, 04:57 PM   #3
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Location: Prairie City, Ia
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Re: Cummins Wiring Interface

If it's a 96, and an auto, it's a 47re. You're going to need the pcm from that truck to control the transmission. The trans needs to see a throttle position sensor, which is on the injection pump throttle bracket, vehicle speed, on the tail housing, govenor pressure from the valve body, and something else but I can't remember. You can wire it in without the entire truck harness. As far as what other gauges you need, that's up to you. If you'll be towing you'll want at least a pyro pre turbo, boost gauge, trans temp gauge, and your engine oil pressure, coolant temp, and voltmeter. You can get a stand a lone controller and valve body from sun coast transmission for the re's too and eliminate the need to use the doege pcm and harness.
1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread
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Old 07-15-2015, 01:38 AM   #4
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Re: Cummins Wiring Interface

Auto Transmission electronic controls are way above my head.

You can start the 12 valve with fuel, 12v to the starter, and manually hold the fuel shutoff lever up. I apologize if you are already aware of how simple the electronics are in these. As far as aftermarket gauges. See below.

Temp sending: Same as chevy, just adapt an electronic sending unit in the place of the cummins one, or at the spare opening at the t-stat housing. might be a separate size sender porthole.

Volt: same as chevy, connect to alt/battery circuit

Oil Pressure: Same as chevy, i used electronic sender in place of cummins one near oil filter.

Fuel: same as chevy, match the sender Ohms that you are using

Speed: Same as chevy, match to senter at tailhousing of trans or Tcase

Tach: This is the only one that get complicated. The cummins has no "ignition" like a gasser that sends off of distributor pulses. you will need to get an RPM reading either from the alternator or the rotating assembly. The easiest way in my opinion was to use the cummins RPM senser, and hotwire it to send a RPM pulse to the tach, basically fooling the chevy tach into thinking its getting an RPM signal. Let me know if you want more info. Basically using a radio shack resistor in the tach wiring.

EGT: this is an extra that you should have. I bought a digital EGT gauge, sender just threads into a tapped hole in the exhaust manifold

Boost: this is an extra that you should have. I boght a matching digital, sender taps into intercooler piping.

Trans Temp: you should have this towing with auto, but above my head.

Pics of mine for reference to gauges that i made work. Oil, Temp, Fuel, Volt, speed-VDO Tach, boost, egt-Autometer
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