86Ranger Jump Started BACKWARDS!

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Aug 2, 2003 | 09:40 AM

rangerte

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Junior User

Joined: Jul 2003

Posts: 74

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From: SoCal

86Ranger Jump Started BACKWARDS!

Had A No Start Condition.Tested For Spark at Coil and Plugs,OK. Tested Fuel Rail for Pressure,none.Tested Fuel pump at Battery,worked.Inertia switch,OK,Fuse ,OK.Got new Relay and EEC-IV Computer.Still same problem.Tested Fusible Links,OK,at Starter Solenoid.Apparently my Neighbors kid had Jumped Started it and reversed the Jumper Cables because someone had used a Red Positive cable and connected it as a negative cable!The Red cable from ground is going to the Negative Post and the other cable is to Positive.I talked to Flatrate tech Forum and my Bro-In-Law(Ford Tech).They said Kiss Computer ,Bye Bye!And anything with a Diode in it!We have no Check Engine Light on with key in on position.Anyway to test the new ECU? Or self Diagnose?No power to Fuel pump connector at Frame Pump.Power to Relay and Inertia Switch,and Diagnostic Connector Under hood!1986 Ranger 4X4,2.9L.V6,Stck.Can ya help me help this Young Bull Rider make it to Rodeo?I think I've tought him how to Jump Start!Don't count on a Red Cable Being Positive! Thanks,RangerTE,02 Ranger XLT Supercab,4X4 OffRoad.

Aug 2, 2003 | 11:02 AM

Mike W

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Joined: Apr 2002

Posts: 7,157

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From: Central Kali

86Ranger Jump Started BACKWARDS!

Usually electronic equipment will have a protection diode to prevent damage from reverse polarity. This is a diode that is connected across the input power leads.

If power is reversed, it will conduct and blow a fuse. Often the diode will become shorted and must be replaced.

An alternator will have it's diodes blown open or shorted because a battery reversal will have a direct path to ground thru the diodes.