Digital dash for '93 Explorer. Do original sensors do more than just provide readings

[scoodidabop]

So here's what I'm thinking about using:

http://www.intellitronix.com/5-gauge-panel.html

The unit comes with replacement sensors based on the make and year of your vehicle to use with the digital panel. My concern is that some of the OEM sensors (oil, voltage etc...) serve more functions than just delivering a reading to the gauge cluster. Does the temp sensor reading help the computer adjust water pump flow and turn on the condenser fan? If all these sensors serve additional functions I wonder if I can simply splice into the wires on some of them and leave the original sensor in place without impairing any operational functionality.

Why digital? Well I have to fabricate a custom dashboard to use in my Jurassic Park Explorer and the original gauge cluster is a bit too bulky to build in to the custom dash. While hi-beam and turn signals are built into the Intellitronix cluster I can sneak the "check engine" other indicators into other sections of the dash with some creative placement.

 

[Anime]

The water pump flow is determined by the engine RPM, since the water pump is driven by the serpentine belt attached to all the other engine accessories. The radiator and A/C condenser fan is driven by a fan clutch, which gets it's marching orders from the thermal sensor attached to it, and engages/disengages depending on the temperature of the air flowing through the radiator/condenser. Neither of these are electric devices or even connected by wires.

The PCM/ECU does get a lot of it's information from engine sensors though, from the throttle position sensor to the mass airflow sensor, they all tell the ECU how much air and fuel are going into the engine at any given moment, and it adjusts things according to the throttle load and everything else.

You should be able to tap into the sensors, or just use the input wires for the stock gauges from the stock sensors rather than using the sensors that come with the aftermarket gauges.

 

[Jason94sport]

Not much electronic on a 93. The speed sensor uses a gear tooth with a cable going to the speedo gauge.

 

[scoodidabop]

The water pump flow is determined by the engine RPM, since the water pump is driven by the serpentine belt attached to all the other engine accessories. The radiator and A/C condenser fan is driven by a fan clutch, which gets it's marching orders from the thermal sensor attached to it, and engages/disengages depending on the temperature of the air flowing through the radiator/condenser. Neither of these are electric devices or even connected by wires.

The PCM/ECU does get a lot of it's information from engine sensors though, from the throttle position sensor to the mass airflow sensor, they all tell the ECU how much air and fuel are going into the engine at any given moment, and it adjusts things according to the throttle load and everything else.

You should be able to tap into the sensors, or just use the input wires for the stock gauges from the stock sensors rather than using the sensors that come with the aftermarket gauges.

Well that's good news. The gauge has speed, oil pressure, fuel, temp, and voltage so it seems all of those sensors don't serve critical engine functionality, correct?

 

[NICE59FORDF100]

As with any aftermarket digital gauges, the devils lies in the details. The reason they send sensors with their clusters is because of the resistence values that indicate the gauge itself. For instance ( A grossly simple explaination)

A ford coolant temp sensor is between 1 and 10 OHMS (just as an example)

The coolant guage on the dash reads this as either 1 OHM = 100 degrees, or 10 OHMS as 200 degrees, and everything in between..


The aftermarket digital guages supply their own sensors because, hey, what if their ECT sensor is 50 ohms = 100 degrees / 200 ohms = 200 degrees? That's why its never usually a good idea to start interchanging sensors that work with one but wont work well with the other.

As far as the pcm, on a first gen anyway, the input sensors are CKP, MAF, ECT (there are two of theses, one for the guage, one for the pcm), TPS, IAT and 02 Sensors. None of these interface with the operation of the guages on the dash. So, in your instance, adding a digital guage cluster will not impede PCM function (the alternator regulator check circuit, however, will be affected until you hook up your dummy lights as per stock wiring)

So yea, it can be done, but you have to use the sensors they provide you to do it. Only exception to this would be the oil pressure switch, as it is either on or off, not variable dependent on actual oil pressure. The Tach would be tricky unless the digital gauges can interpret the PIP and SAW angle signal generated from the ignition module. Same with the VSS (although most vss sensors [if they are hall effect type] run the standard 8000 rev per mile)

Hope this helps!

 

[NICE59FORDF100]

you might wanna give this thread a read if you havent already...the theory allows you to use stock ford components with the sensors you already have in the truck...

http://www.explorerforum.com/forums/showthread.php?t=257233&highlight=digital+dash+swap

 

[scoodidabop]

Thanks NICE. That thread is crazy btw! Lots of info there...

So there are two connectors down near the oil pan (easy to remember since I just swapped the motor) one near the front of the engine and one back and a little lower, almost parallel with the oil drain plug. Is the one toward the front the pressure switch? Since the connector near the rear of the motor sits a little lower on the pan so it seems more likely to be the oil level gauge (add/check oil light?)

You mentioned hooking up dummy lights for the alternator regulator check circuit but what exactly does that mean and how will the circuit be affected without the dummy lights?

The gauge cluster I'm looking at doesn't have tach so no worries there and the impedance is controlled via dip switches on the back so you can change it for different makes.

 

[NICE59FORDF100]

The sensor toward the front of the motor on the driver side is the oil pressure switch...Should be a W/R single wire the just kinda 'pops' onto the sensor. The sensor itself looks like a grey plastic acorn.

The sensor in the pan is the low oil level indicator, and a single wire (W/PK wire). It illuminates the 'Check Oil' light on the dash that is right next to the 'Check Engine' light when oil level drops about 2 quarts too low. Also, the 'Check Oil' light should illuminate or 'Prove-Out' when the key is in the start position.

The alternator charging check circuit is basically one that is hot in run, goes though the Battery light/500 ohm resistor circuit in the instrument cluster, and then to the alternator. It will be the LG/R wire. Its a way for the voltage regulator that is internal to the alternator to check itself that the voltage output is correct. If, for instance, the voltage drops to 11.5 volts, the internal regulator turns on the battetry light. And without voltage going through the 500 ohm resistor (like if the instrument cluster is unplugged from the truck, creating an open) the internal regulator will detect a fault and not allow the alternator to charge, hence the vehicle will not start/or start and die.

 

[scoodidabop]

I see, I see. Thanks for your insight its a huge help!

So the alt. circuit ties into the battery light but does it also connect to the voltage gauge that's above the temp gauge? In any case I will preserve all the check lights including their circuity to integrate into the new dash below the digital gauges so hopefully I can avoid any faults in the electrical system.

 

[NICE59FORDF100]

The volt guage itself receives voltage from the LB/R wire on connector C222, so it is separate from the Battery light

 

[scoodidabop]

The volt guage itself receives voltage from the LB/R wire on connector C222, so it is separate from the Battery light

Perfect. Thanks again for the info. I bet it'll make even more sense when I get it all opened up and can see some of the components you're talking about. Whenever I get it all in I'll be sure to update the thread.