Chrysler RAM50/D50/Arrow 1979-1993 Repair Guide

Glow Plugs


The glow plug system is a preheat system which rapidly warms the combustion chamber during a cold start. This initial heating allows the fuel to burn quicker, resulting in better cold driveability.

The earliest diesels required the driver to wait while the glow plugs worked; when the correct temperature was achieved, the engine could be started. Dodge eliminated this long wait with what they call the Super Quick Glow System. By using both relays and a dropping resistor, the plugs are brought to their operating temperature almost instantly. The engine may be started within 5-10 seconds. Additionally, when the engine is running and the coolant temperature is below 130°F (55°C), the glow system will remain engaged, resulting in stable heat generation and reduced engine noise.

The glow plugs themselves are nothing more than resistance heating elements. Because they heat quickly, they consume heavy amounts of electricity. The high amperage required is conducted through a buss-bar (solid conductor) connected to each plug. It is important that the battery in a diesel vehicle be kept fully charged; otherwise the draw of the glow plugs combined with the draw of the starter will drain the battery.


  1. Disconnect the negative battery cable.
  3. Loosen the small nut on the top of each glow plug.
  5. Remove the glow plug plate (buss-bar) running among the 4 plugs.
  7. Carefully unscrew the plug from the head, using a 12mm, deep socket. Handle the plug carefully, protecting the tip at all times. If the unit falls or strikes a hard surface, it must be considered unusable. (The heating element inside the tip is a winding similar to the filament within a light bulb; it will break under impact.).
  9. The glow plug may be tested with an ohmmeter. Check resistance between the top terminal and the body of the plug. The correct resistance is 0.23 ohms; make certain the meter is set on the correct scale to read this value. If there is no resistance or excessive resistance, the plug is unusable.
  11. Inspect the buss-bar for any damage to the protective coating.
  13. Install each glow plug with your fingers. Take great care to install the plug straight into the port, protecting the tip from impact.
  15. Once each plug is finger-tight, use a wrench to tighten the plug to 13 ft. lbs. (17 Nm).
  17. Install the buss-bar to the glow plugs. Make certain the retaining nuts make firm contact and tighten them to 1 ft. lb. (1.4 Nm).
  19. Connect the negative battery cable.