Adding "Home-Built" Daytime Running Light Circuitry To 95 LeSabre

I am building circuitry to run the high beams of my 95 LeSabre at low intensity while the car is in gear (reverse, all drives).

Because I do not want to run the daytime running lights while the engine is running but in park, I need to find out if there is a wire I can tap into that is energized with 12v only when the car is out of park. Or similarly, are there wires I can tap for each different mode of the steering column shift lever. For example: Reverse, Drive, Drive 2, etc. Even Neutral is fine.

Again, I do not want to run DRLs when the car is in park.

I need to pull 12v and maybe 100mA or less from the circuit in question in order to energize a relay which will activate my daytime running lights. Also I would prefer to tap into the circuit in question UNDER THE HOOD (not under the dash) as the circuitry box I am adding will remain under the hook.

Can someone help me identify where I can find such circuit before I am forced to start trial and error?

Thanks!

Uh, start with a proper manual for a wiring diagram. You want to look for the park/neutral switch and the wiring for said switch. You can also get the diagram from alldata.com for a subscription fee for your vehicle.

Be careful with the transmission range switch. If the inputs to your device are fairly high impedance, there should be no problems. The PCM uses the signals from the switch for various functions, including the logic to shift the transmission, operate the TCC, operate door locks, and various other functions.

Thanks all. Great suggestions.

The impedence on the relay coil is about 80 ohms. At 12v the relay draws about 150mA.

I stopped in the autoparts store today, looked in a Haynes repair manual and found the wiring diagram. However, the diagram is not clear; It is only shows the common to be grounded at the neutral position for all 4 poles. Obviously some information is lacking.

I still would like to be able to power the DRLs while in R, N & D. I wonder if the ECM has an output that is "hot" while the transmission is in one of these drives.

Otherwise, I'll connect the DRLs to run when the key is switched on. I just don't like that though.

I'm hoping someone that reads this has some experience in this area.

Thanks :grinyes:

You need the factory wiring diagram, which can be obtained from alldata.com.

I still would like to be able to power the DRLs while in R, N & D. I wonder if the ECM has an output that is "hot" while the transmission is in one of these drives. Thanks :grinyes:
The answer to the above is NO!

IIRC, the pink wire to the P/N switch is hot only with the ignition switch on, and it is supplied from fuse #10 (20 amp)! When you move the selector to reverse, the switch provides power to the back-up lights through the light green (LG)wire. When you select drive, it provides power (12v) to the network of solenoids for shift functions through the red wire (E) terminal on the transmission umbilical cord. When the PCM has determined, through it’s network of sensors, that it is time to energize a solenoid, the PCM Quad Driver will complete a ground circuit to the solenoid that needs to be energized. The PCM does not provide 12v to anything on the transmission. The only power feed from the PCM to the transmission is for the temperature sensor (5v) and in return, the PCM receives variable voltage back from that sensor to interrupt fluid temp. (Works the same as the CTS)

OK thanks for that detailed information. Looks like I'll be drawing power from a circuit that is energized based on the key turned in the run position, like how everyone else's DRLs work.

Thanks again.