Archived Electronics

[2-ND TIME]

Dodge Ram

Referring to 24V Turbo Diesel 1999 Model Year Wiring diagram for ECM part # (3942336) Bulletin # 3666480

Accelerator Pedal Idle Validation Circuit Resistance for on and off - idle states

Maximum closed circuit resistance <125 ohms

Minimum open circuit resistance >1 k ohms

between supply and return wires 2000 to 3000 ohms

between supply and signal wires (released pedal) 1500 to 3000 ohms

between supply and signal wires (depressed pedal) 200 to 1500 ohms

NOTE: released resistant - depressed resistance must be 1000 ohms

Can you turn on a transistor with this kind of excessively high resistance?

 

[John - K5AWO]

OH yeah, bi-polar (PNP or NPN) transistors can be turned on with resistances higher than 100K ohms. Depends on the hfe, beta (gain) of the transistor and how much collector current is being controlled. Divide the collector current by the gain factor and that is the required base drive current. As long as the voltage is high enough / resistance low enough to force more current thru the base junction than the value obtained by the equation, then the transistor will turn 'on'.





FETs (field effect transistor) have input impedances measured in meg-ohms. They are voltage controlled, not current driven.