From what I understand, this is what I need:
L31:
1. +12V from battery
2. +12V during Start & Run
a. +12V to fuel pump during Start & Run
b.
3. Signals for Tach, water temp, oil pressure, & VSS from trans to come from their respective sensors > through the L31's underhood fuse block > then through the fire either INTO the Regal's fuse box or bypass it > then to the dash (Dakota Digital)
Regal:
1. Leave it be as much as possible since it will only be controlling things like wipers, lights, horn, radio, maybe a/c, maybe cruise control.
Sound about right?
Yes, you are on the right track. Go back to the diagram I posted on Feb 13. Using the numbering system from above:
1) +12V from the battery is shown on the left hand side of the diagram, note the battery supplies PCM directly, orange wire ckt 440; the other ckt shown DLC ckt 840 is to the connector where they hook up the device when they inspect your vehicle
2) +12V during Start & Run. You need a fair amount of amperage so you dont want to get this from your Regal harness, instead you want the Regal system to send a signal that the ignition switch is in Start & Run. Look at the top most relay labeled PCM RLY. The Regal signal (most likely the +12V to the original coil) is attached to 86 of the relay. When the signal comes from Regal to 86 the circuit is complete to ground through 85. This energizes a coil in the relay which closes the contacts and the circuit is closed between 30 and 87, current is then made available to the loads downstream of 87. The reason that the relay is desirable is that the load on the Regal harness is less than 1 amp (current from 86 to 85) whereas the current through 30 and 87 is limited by the rating of the relay, typically 30 to 40 amps. In actuality, I found about 60 amps were needed so I used two relays and broke up the loads between them.
a) for the fuel pump, the signal to energize the pump comes from the computer, for my vehicle it is a dark green wire coming from computer connector 4, pin 1. The relay works the same as described above.
As for the instruments, the wires do not run through either fuse box, the wires run directly from the sensor or computer to the gauge.
1) run the tach wire in the L31 directly to the gauge
2) water temp- the Dakota digital system probably came with its own sensor (or told you what to buy). You will need to install the sensor and run a wire from the sensor to your gauge.
3) oil press- same as water temp, use sensor supplied by Dakota digital; the L31 has two oil pressure sensors-- one for the gauge and the second keeps the fuel pump running after the engine starts. I will provide a diagram to show you that circuit.
3) VSS run from computer to your gauge, again does not go through either fuse box; you need to ensure that the computer signal is compatible with Dakota digital, should be
If you took the cruise control unit off the L31, then you will want disconnect all the Regal wiring and use the L31 computer to operate the L31 cruise control module. You will have to run the wire from the L31 system to your old Regal cruise control switch.
I also used the L31 crank start circuit. I'll provide a diagram for that circuit, too.
Mike
