2.3l to 4.0l swap clutch start fail

[nostrebor75]

Hi, i have a 91 ranger that just had a 4.0 transplanted into it. The truck originally had a 2.3l with a manual tranny. The 4.0 donor came out of a 92 Explorer 4x4 with an auto matic, but the automatic was trashed so the 4.0 was mated to a manual trans, not from the 2.3, but another 4.0. The wiring harness and computer was also used from the Explorer. The problem I'm having is, the engine will not start. It will turn over messing with the starter and solenoid, but a clutch and key start will not happen. Does any know if the computer matters in this particular setup, or if some more wires need to be spliced to make this work. My mechanic, who is trying to complete the swap, is at a loss. Any ideas or insight would be appreciated, and I'll try to answer any questions to the best of my ability...

 

[RonD]

Computer will not be the problem for starter motor not being activated by the key.

Manual trans starter motors are different from automatic starter motors, different gear and nose length, just FYI.

Explorer automatic wiring will have a Clutch Switch by-pass plugged into the clutch switch connector above the clutch pedal.

Ignition switch-----------Clutch pedal by-pass---------------------------Automatic's NSS switch-----------starter relay

So this Bypass needs to be unplugged and the clutch pedal connection plugged into a Clutch switch and installed on the clutch pedal push rod.

Ignition switch-----------Clutch pedal switch------------------------------------starter relay

OR

There will be a Pink wire coming out of the ignition switch, that wire will have 12volts when key is turned all the way to START.
Splice into that wire and run a wire to the Starter relay on the inner fender, by-passing every thing

On '92 the Battery's larger positive cable should run directly to the Starter Motor.
Then the smaller cable from positive to Starter Relay, other larger post on starter relay will have a Black wire that runs to the starter motors smaller post.

Then Red/Blue wire(from clutch switch) connects to starter relays small "S" post.
OR the wire you run to by-pass it all.

When you turn the key to START the Starter relay on the fender gets 12volts and closes.
When it closes 12volts is sent from battery to small post on starter motor.
This 12volts activates the Starter Solenoid, the solenoid does two things, it pushes out the Starter motor gear to engage the flywheel and it also closes internal connection so starter motor gets full battery power from the larger positive cable hooked directly to the starter motor.

 

[AllanD]

The Main engine/engine bay harness for a 4.0 is basically the same within any given model year, but there is a "sub-harness" that connects on the inner fender below the brake master cylinder that connects the engine instrumentation and the transmission connections.

This harness for the automatic carries the connection through the Neutral safety switch
(not to be confused with the Neutral SENSE switch of manual transmissions to 1993)
The manual trans harness also has a short loop of wire that jumpers the Neutral Safety Switch to allow starter actuation on the transmission side of the connector(s)

There are two connectors one grey one black, to connect this harness... this harness connects the
oil pressure switch, the temp Gauge sensor, the oil pan mounted engine oil LEVEL sensor as well as
the switches on the transmission and by the way the "Canister purge solenoid" for the evaporative emissions
system.

This harness I'm talking about could technically be called a second (or third) "On ENGINE" harness the primary dealing with engine management (ECT, TPS and injectors)

AD

 

[nostrebor75]

Thank you for this info. I will pass it on to my mechanic, and see what he can do with it.

 

[Jimmyrig]

A possibility would be the deleted prindle switch (spelling). It mounts on the shift lincage on the old automatic transmition. They have to be adjusted almost perfectly for it to allow the engine to turn over. Sinice the auto was scrapped it didn't get hooked up. Find the wires for that, probably hanging below the drivers side, and use a diagram to find the wires that cut off the starter relay. Then you can either splice them together or hook them to the switch on the clutch pedal