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Can anyone tell me the correct voltage for the various sensors in a 94 Jeep Wrangler 2.5 engine? The pcm has (2) voltage values noted:

5v on pin #6 and 8v on pin #7.

I assume the coil receives 12v but what about the engine management sensors?

Thanks
 

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Can anyone tell me the correct voltage for the various sensors in a 94 Jeep Wrangler 2.5 engine? The pcm has (2) voltage values noted:

5v on pin #6 and 8v on pin #7.

I assume the coil receives 12v but what about the engine management sensors?

Thanks
Hi BorderGuy,

Try posting this over in the YJ tech forum. You'll have better luck there.

Welcome to the forum!
 

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Discussion Starter #3
Thanks...made that post a month ago...no responses.:jawdrop:
FYI: I figured it out and got the Wrangler running...they had the wrong harness in it..had to re-pin it.
 

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Can anyone tell me the correct voltage for the various sensors in a 94 Jeep Wrangler 2.5 engine? The pcm has (2) voltage values noted:

5v on pin #6 and 8v on pin #7.

I assume the coil receives 12v but what about the engine management sensors?

Thanks
The 5v and 8v are reference voltages. These voltages are supplied to several of the sensors...usually hall effect type sensors. These type of sensors are 3 wires. They have a voltage supply (8v or 5v), a ground, and a signal. The PCM doesn't require 8v or 5v, its supplies it to the sensor to get the sensor to work properly. It also needs a ground, that ground runs back through the PCM. The signal wire on these is what is inputted into the PCM.

There are typically 3 sensors that utilize the 8v reference line. The crank sensor, the cam sensor (sometimes referred to as the Cam Sync) and the vehicle speed sensor. All 3 of these sensors produce a square wave signal back on the signal wire to the PCM. This is how the PCM can figure out where in the rotation the Cam and Crank are. Usually there is a tone ring or segmentation in the steel that runs by the sensor. The square wave is a 0v (or close to), then goes to close to 8v then back to 0. You can look up crank signal wave forms to see what it will look like. Each mfg is a little different.

The 5v reference circuit is used for both the MAP sensor and the throttle position sensor. Each of these also requires a ground and has a signal wire back to the PCM. In the case of these there is a voltage that is sent back to the pcm, somewhere between 0-5v depending on what the sensor is reading. I will see if i can look up what they are and get back. Sometimes those values aren't always published, like we wish they'd be.
 

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Don't have a chart for the TPS but here is what the service manual says:

The TPS output voltage (input signal to the
PCM) represents the throttle blade position. The
PCM receives an input signal voltage from the TPS.
This will vary in an approximate range of from 1 volt
at minimum throttle opening (idle), to 4 volts at wide
open throttle.
 
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