Lights on engine stalls

[XBRIT]

Hi, When the motor is at operating temperature and I switch on the lights, heater, brake lights etc the engine will not idle it stalls. Any ideas
72 E body 383 4 speed.

[dodj]

Putting a high load on the electrical system at idle will drop the voltage. In stock configuration, it was pretty weak at idle to begin with. The lower voltage will reduce ignition power. Upgrading your electrical system with relays for the lights will help.

[XBRIT]

Ummm does that mean a relay on all the electrical devises?

[Chryco Psycho]

unless you are running some high power headlights it should not be drawing enough load to stall the engine , is the battery OK & the alt turn freely ?

[ChallengerHK]

unless you are running some high power headlights it should not be drawing enough load to stall the engine , is the battery OK & the alt turn freely ?

   Admittedly, this is 30 years later, with 30 extra years of corrosion, but I used to frequently drive my car at night in winter. Lights on, fan running, wipers running, radio on, and it didn't stall.

[dodj]

Ummm does that mean a relay on all the electrical devises?

Typically just the high and low beam lights, and bypassing your ammeter connections.

If you turn on the devices listed and your car stalls, it is the system voltage dropping. Without enough primary voltage for the coil, the secondary voltage will not be enough to jump the spark plug gap. The exact reason for the dropping system voltage could be many though. As CP says, weak battery and/or alt. Short cct in any of the ccts you mention turning on. Shorted/compromised windings in your blower motor, blower motor switch, corrosion in connections causing voltage drops, bearings in your blower motor causing high load, ...etc.