I know this website is for b bodies but i own an R body (extended b body) and there very similar. My issue is on my 80 newport my lowbeams only work when my highbeams are on. Only way to have lights is to turn highbeams on. I have replaced the highbeam switch but no difference. I need help
The headlight circuit on the 1980 Newport consists of the headlight switch, wiring to the dimmer switch, the dimmer switch (steering column mounted), two wiring circuits from the dimmer switch, through the bulkhead disconnect, to the headlamps. The outer mounted headlamps are dual filament, high and low beam. The inner mounted headlamps are single filament high beam only. Most Chrysler four headlight systems, and two headlight systems as well with only two low/high beam lamps and no separate high beam lamps, operate similarly, although earlier vehicles used a floor mounted dimmer switch.
As shown in the following wiring diagrams from the 1980 factory service manual, the headlight feed circuit starts at the headlight switch "H" terminal which feeds via the light green wire (L2-14LG) to the dimmer switch terminal "B". The dimmer switch switches between high beam terminal "HI" and low beam terminal "LO". The "LO" terminal feeds the low beam filaments in the outer headlamps via the violet with tracer wire (L4-14VT*) through bulkhead cavity location #40. The "HI" terminal feeds the low beam filaments in the outer headlamps via the violet with tracer wire (L3-14RD) through the bulkhead cavity location #39 to L3-14RD*. The circuits are completed after the headlamp filaments through black wires L9-20BK and L9-16BK to ground lugs.
When the headlights are on high beam, only the "HI" filaments are illuminated in both inner and outer lamps. When the headlights are on low beam, only the "LO" filament in the outer lamps is illuminated.
Because your high beams operate in all four lamps when switched on, the power to the headlamp switch, the switch itself, the feed to the dimmer switch, and the "HI" circuit is operating. The "LO" circuit is not functioning and has one of the following issues:
- Both low beam bulb filaments are bad. 4656 is the base number for most brands of low beam lamps. H4656 for halogen.
- The dimmer switch is bad, possibly even the new one as well.
- The linkage from the multi-function stalk to the dimmer switch is not engaging the low contact correctly and might need adjustment. Adjustment might be made with the slotted mounts.
- The "LO" circuit wiring has a break or high resistance point either inside the car or in the engine compartment.
- The connection at bulkhead cavity #39 has a problem.
After verifying the lamps and dimmer switch are good, tracing through the wiring and connections will be required.
If you don't have one, a 1980 factory service manual is very helpful. These are not available online like earlier manuals at mymopar.com, but can be found on eBay and other literature places. The 1980 manual is a two volume set:
