Glow Plug Operation - Diagnosis/Usage
File In Section: 6 - EngineBulletin No.: 57-64-06
Date: November, 1995
INFORMATION
Subject:
1996 Glow Plug Operation, Diagnosis and Usage, Servicing 1992-96 Glow Plugs
Models:
1992-96 Chevrolet and GMC Truck C/K, G, P Models
with 6.5L Engine (VINs F, P, 5, Y - RPOs L65, L49, L56, L57)
The 1996 trucks with 6.5L diesel engine use an 11G glow plug, service part number 25168651. This glow plug services all 6.5L engines. The 11G glow plug is a positive temperature coefficient plug that limits the current to the heating element as the plug heats up.
1996 Glow Plug System Operation
The pre-glow times remain approximately the same as previous model years. For 1996 the post-glow cycling is activated sooner (within two seconds), after the pre-glow cycle is completed whether cranking engine immediately or if customer waits before cranking. This change will maintain engine combustion temperatures for better starting of the engine. A technician or customer will notice the glow plug "wait" light on more often during the initial start and/or initial running of the engine as compared to 1994-95 model years. The amount of post-glows and duration of glow plug cycles is determined by engine temperatures, barometer, altitude and battery voltage.
Diagnostic Information
1. Ignition "off".
2. Disconnect all glow plugs.
3. With a test light connected to B plus (battery positive terminal), probe the spade terminal on each glow plug.
4. Do all glow plugs turn test light "on"? If yes, glow plugs are okay. If no, replace glow plugs that do not turn "on" the test light.
If an amp meter is used, it must have a "peak/hold" feature connected prior to turning ignition on for correct readings. If not, unnecessary replacement of a glow plug could occur. The amp meter will indicate decreasing current within the "key on" time period while the "wait" light is on. A subsequent or second attempt with "key on" cycle will result in even lower readings on the amp meter. Prior to replacing any 11G glow plug checked with an amp meter the test light method should be used for verification to avoid unnecessary replacement of a glow plug.
Servicing All Trucks with a 6.5L Engine
1. DO NOT INSTALL A 9G GLOW PLUG INTO A 1996 TRUCK WITH A 6.5L DIESEL ENGINE (9G part number 25163212 was released in prior model years).
2. USE 11G GLOW PLUGS FOR ALL 6.5L DIESEL ENGINES (regardless of model years). The 11G glow plug can be intermixed on 1995 and prior model years that have existing 9G glow plugs.
3. The 9G glow plug is only applicable to the 6.2L (LH6, LL4) diesel engine.
Parts Information
Part Number Description
25168651 Glow Plug (11G)
Warranty Information
For vehicles under warranty, use:
Labor Operation Labor Time
J4760 (right) Use published labor operation time.
J4761 (left) Use published labor operation time.
J4767 (both) Use published labor operation time.