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6.5L Diesel Engine Discuss the 6.5 GM diesel engine & associated components. Automatic transmission questions & problems belong in the 4L80/85 - 4L60E - 6L90 Transmission Forum


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Old 03-23-2020, 10:26 AM   #11 (permalink)
57diesel
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How about at the relay socket? If you pull it out they usually have a diagram on them showing the pin numbers and locations. The switch contracts are 87 and 30. I don't remember which is which but one of those should be +12 all the time and the other one is the one that leads down to the pump. IF you have power at one of them and then install a jumper between them that should send power down to the pump.

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Old 03-23-2020, 10:28 AM   #12 (permalink)
Twalch0301
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I’ll test that when I get home. So one should have constant power and the other should have power with the key turned?

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Old 03-23-2020, 11:17 AM   #13 (permalink)
Glagulator
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Does the ORANGE wire at the OPS have 12v. all the time.
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99 CREW LONG SRW C3500 work truck 199k+ mi. orig. motor & trans 4.10, modded engine harness, new oil cooler & lines, all new front end parts and poly bushings, trans poly mount, all new brakes.
96 SUBURBAN K2500 wife's truck 210k+ mi. orig. motor & trans, 3.73...
95 C2500 Suburban 6.5td HO w/p, timing set, HB & pulley, all rubber hoses, modded engine & main harness, converted to OBD2, PMD to bumper...
95 C1500 Suburban 6.5td rebuild tranny, convert to DB2, replacing as many parts as I can.
96 C2500 Suburban 7.4L converting to 6.5td w/ DB2, 4L80, 3.73
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Old Yesterday, 08:18 PM   #14 (permalink)
uberhund67
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your 30 pin should be power all time
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Old Yesterday, 08:48 PM   #15 (permalink)
Twalch0301
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Thanks for the info. Hoping to try out some of this week or weekend at the latest and let everyone know what is going on
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Old Today, 05:28 AM   #16 (permalink)
serDenis
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May come in handy
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Old Today, 09:42 PM   #17 (permalink)
buckskin0369
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I don't understand why people keep chasing this gremlin . Just run a ground from your lift pump to the frame and a fused hot wire from any wire that's hot with the key on . The way these things are wired from the factory with the OPS is just a safety so if you lose oil pressure it will shut down the engine to prevent further damage . A little heads up IT WILL RUN LONG ENOUGH TO DESTROY IT ANYWAY .
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Old Today, 09:56 PM   #18 (permalink)
Glagulator
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The OPS is there to stop the lift pump in the event of an accident.
It is not foolproof, but if you were stuck in your upside down truck and the lift pump was pumping fuel all over the place....
Unlike gas engines, these diesels will run just fine with the lift pump not working.
Not recommended, but that is the way it is.
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There are 10 kinds of people in this world; Those who understand binary and those who don't.

99 CREW LONG SRW C3500 work truck 199k+ mi. orig. motor & trans 4.10, modded engine harness, new oil cooler & lines, all new front end parts and poly bushings, trans poly mount, all new brakes.
96 SUBURBAN K2500 wife's truck 210k+ mi. orig. motor & trans, 3.73...
95 C2500 Suburban 6.5td HO w/p, timing set, HB & pulley, all rubber hoses, modded engine & main harness, converted to OBD2, PMD to bumper...
95 C1500 Suburban 6.5td rebuild tranny, convert to DB2, replacing as many parts as I can.
96 C2500 Suburban 7.4L converting to 6.5td w/ DB2, 4L80, 3.73
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