# 93 truck won't start, need advice



## 93kingcab (Aug 27, 2007)

1993 Nissan King Cab 4 cyl 5 spd truck won't start. 
It's been acting up for a few years. You'd go to turn the key and it wouldn't turn over, you'd try it again and it would fire right up. All the dash lights and everything would be fine the engine just wouldn't crank. It only happened a couple of times per week for a while, then it started getting worse recently. Now it won't turn over at all. 

It's not the battery, i put jumpers on it from another car and it won't turn over. All the lights and everything work fine and don't seem dim or sluggish. The battery terminals are clean.

It's not the starter, i pulled it and took it to Autozone. They tested it more than 6 times and it worked perfectly.

It's not the clutch sensor. I disconnected it and shorted it with a wire. I can hear the solenoid click when it's pushed in, but not when it's disengaged.


What's the next thing I should check?


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## Humanure (Feb 15, 2007)

Check the ignition switch.


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## smj999smj (Jan 1, 2006)

Locate the interlock relay on the passenger side of the engine compartment; it is a blue relay that has two harness connectors plugged into it and it's not far from the battery. If you can duplicate the no-start, try tapping on the relay a few times. If it starts, you probably have a sticking interlock relay and need to replace it.

The interlock relay has a switch side, which when closed, completes the circuit from the ignition switch to the starter solenoid. The switch side closes when the solenoid side of the interlock relay is "energized" and creates a magnetic field that causes the switch side to close.

Each of those connectors at the interlock relay have a B/Y wire. Those wires should have battery voltage when the ignition switch is turned to "START." If not, check your ignition switch, fusible links, and the circuit between the interlock relay B/Y wires (which splice together to form one circuit) and the ignition switch.

The B/P wire at the interlock relay goes to the starter solenoid. Applying 12 volts to that wire should cause the starter to crank the engine (make sure the trans is in "neutral").

The last wire is the L/G (blue w/ green tracer) wire which is the ground circuit for the interlock relay solenoid. The LG wire should have continuity to ground when the clutch switch circuit is closed. So, the ignition switch is turned to "START," applies battery voltage through the solenoid windings in the interlock relay to the clutch switch at the pedal. If the clutch pedal is pressed to the floor, the clutch switch closes and completes the circuit to a ground, causing the solenoid in the interlock relay to energize, create a magnetic field which pulls close the interlock relay switch side, which in turn, allows the power from the ignition switch to flow to the starter solenoid, and thus the starter should crank.


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## 93kingcab (Aug 27, 2007)

Thanks smj999smj, your advice was dead on right. I replaced the interlock relay with borg warner part # R3273 and it fired right up with no problem


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