need help with a Nissan truck

OBX Fisherman

OBX Fisherman

Well-Known Member
Joined
Mar 21, 2005
Location
Winston-Salem
Buddy at work has a 94 Nissan truck that quit working last week. AAA guy told him the starter was bad. Helped him take out the starter tonight but found the started worked fine. Started using the multimeter and probing around since nothing electrical works on the truck. Battery is good. This is the strange part; with the ignition off, I can read +12V from the negative battery post to the engine block. I read no volts from the positive battery post to the engine. With the battery out, I can read continuity from the positive battery cable to the negative battery cable. Thats sounds like a dead short to me, but with the battery hooked up, no magic smoke is released (or has been released) We've pulled all fuses and still read +12V negative battery to engine. We've disconnected ignition switch and still get the same reading. :dunno: Thoughts?
Gary
 
hey gary, did you continuity test from the positive lead at the battery, to the other end. may want to ohm out that wire as well, alot of corrosion can cause alot of voltage drop...just thinking out loud here, but it wouldnt hurt to check.

jason
 
This is the strange part; with the ignition off, I can read +12V from the negative battery post to the engine block. I read no volts from the positive battery post to the engine.
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I thought that was normal. That's why you always disconnect the negative battery cable when working on the car.

With the battery out, I can read continuity from the positive battery cable to the negative battery cable
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Sounds like you are just completing a circuit with your tester. If it hooks up with no smoke then, I'd say your safe.

As said above, double check the battery cables/terminals. The Nissan factory terminal are very thin. I'd probably check the relay box first.

And while it's on my mind, I think they have a fuse block/link connected to the battery terminal.
 
Those year nissans have a couple of fusible links next to the battery as well.
 
I'm still trying to wrap my head around electrical stuff, so bear with me if I'm wrong. I can only talk about things from my experiences working on my Jeep.

With that said, I'd be inclined to think that you've got a positive lead shorted to a ground somewhere. I don't think you should be reading +12V connecting a lead from the negative terminal to the block. My Cherokee has a battery main running from the negative terminal to the block. I'd think you should read 0 with a lead from the negative terminal to the block. Something doesn't match up though, if it was a positive lead shorted to a ground I'd expect to see a fuse blown or fusible link melted.

With the battery out and continuity from between the battery cables, I'd definitely say a positive short somewhere.
 
My fault, you're right. Negative to ground should be 0, positive to ground should be circuit. (drink anther one.....)

The positive cable is inside a mess of wires running along side the block going to the starter. Check the insulation to make sure it hasn't worn off and is touching the block somewhere.

You could try to bypass the factory positive cable to eliminate that cable being a suspect. When I replaced mine I cut off the ends of the factory cable in a safe manner and zip tied the new one under the existing wad of wires. Nissan was nice enough to leave 0 slack in the cable to replace a terminal.
 
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