Diesel Engine - Glow Plug System Operation
Number: 83-121Section: 6D (VI)
Date: Feb.., 1984
Subject: DIESEL ENGINE GLOW PLUG SYSTEM
Model and Year: 1982-83 MONTE CARLO,
MALIBU AND EL CAMINO
TO: ALL CHEVROLET DEALERS
This cancels and replaces Chevrolet Dealer Service Bulletin 83-121 dated February, 1984 which should be destroyed. This reissue corrects model year usage to the vehicles listed.
The glow plug system used on 1982-83 Monte Carlo, Malibu and El Camino vehicles equipped with V6 or V8 diesel engines contains an electronic module with diagnostic features. In the event of a system failure, the wait light may stay on or come back on after the engine is started. The system is also very dependent on a good ground to operate properly. By a good ground it is meant that it is a zero resistance connection confirmed by the use of a digital volt ohm meter on the 200 scale. Do not overlook the resistance in the meter leads when performing these checks. If it does not get a zero resistance ground, the performance may suffer.
Lack of zero resistance ground accounts for the greatest number of problems in this system.
There are four (4) grounds to be concerned with. First check the battery to engine, the engine to the cowl, (braided strap at the rear of engine), the ground behind the left hand valve cover (G181) and behind the instrument panel to the left of the steering column (G104).
Conditions have been encountered with the glow plugs coming on one time and quickly going off after a Goodwrench engine has been installed. We are finding that the braided ground strap at the rear of the engine has not been reconnected.
The following conditions can cause the wait light to come back on or stay on:
1. Glow plug burned out.
2. No continuity in blue and black wires at the glow plug relay and terminal E at the module.
3. No continuity in purple or gray wire between sensor and module.
4. Bad diode trio in generator.
5. No continuity in brown wire between generator and module.
6. High resistance in blue wire at the glow plug relay and terminal E at the module, or high resistance in the black wire at the glow plug relay and the orange wire with black tracer at the control sensor.
7. Loose glow plug terminals.
8. Poor grounds.