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4.0 Wiring Help


work_in_progress

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89 B2 with 92 Exploder engine. When key is turned, the starter does not engage, and the check oil pressure light comes on. Could it be that the truck is completely miswired, or that the oil sensor is trashed? Help?
 


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RonD

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Automatic or manual trans?

If automatic, check NSS(neutral safety switch) on trans, also try starting in neutral instead of Park

If manual, check Clutch switch on pushrod

With vehicle in Park or Neutral and tires blocked.
Turn key on

Use a jumper wire from battery "+" to the smaller wire's terminal on the starter motor, the "S" connection.
Starter should start cranking engine.
If not then starter motor is bad or battery's larger cables are not passing power.

If starter works then problem is in the ignition switch, NSS(Clutch switch) or the wiring between them

Since you commented on "other lights" coming on, ignition switch under the steering column might be the place to start.
 

adsm08

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Swap wiring is not always easy. Especially when using Explorer harnesses because they don't match anything else perfectly.

Don't worry about some huge systemic problem, you at most have a handfull of small, unrelated issues. Set out diagnosing each individual problem by itself, and fixing each one.


Do like Ron said for checking your start circuits and don't worry about the oil pressure light right now. That is a fairly simple circuit and the light should be on if the engine isn't running. If it still acts oddly once you get her started, then worry about that.


I had my first 4.0 swap driving for a few months before I had all my gauges and stuff working right.
 

SenorNoob

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I've been driving like 2 years now and all my gauges still aren't right. The gas gauge stays on the bottom most of the time. Sometimes it'll go up to 1/4 when the tank is full. If I take the sender out of the tank it works fine....
 

adsm08

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I have two gauges that don't work. My oil pressure and coolant temp.

Oil pressure sender is unplugged because it is bass ackwards to my cluster and oil pressure in the system keeps the light on. Coolant temp doesn't work because I had some mystery loss and dumped some of that Barr's gel in the system, and it sealed the sensor.
 

shadow88

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I had the same trouble when I did my swap, mine was a neutral safety switch on the motor wire harness, my 4.0 came from a automatic and my bronco was a manual, all I did was bypass the switch by taking out the switch, and splicing the two wires together, pink with a blue stipe if I remember right
 


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