Owner's Problem Description
The owner of the 1985 Toyota Landcruiser reported that the vehicle cranks but does not start. The issue was noted particularly in cold and rainy conditions, leading to suspicions about the glow plugs and related components. Previous checks indicated fuel is reaching the injector line, and the owner plans to replace the fuel filter as a precaution. The vehicle started successfully once after previous failures, suggesting an intermittent issue possibly linked to the glow plug relay.
Professional Technical Analysis
The 1985 Toyota Landcruiser is equipped with a 2H engine, which relies on an effective glow plug system for cold starts. The vehicle exhibits a cranking condition but fails to start, particularly in adverse weather. Initial diagnostics indicate that fuel is present at the injector line, suggesting the fuel delivery is operational. However, intermittent starting issues have arisen, likely due to the glow plug relay or the glow plugs themselves. The EDICT motor, responsible for engaging the fuel system, must be verified to ensure it operates when the ignition is turned on. This vehicle's age and typical wear patterns necessitate a thorough examination of electrical connections, particularly under cold and wet conditions where corrosion may impede functionality. The glow plug system should be assessed for proper relay operation, ensuring that the glow plugs receive adequate voltage for sufficient heating. Testing the relay involves checking for continuity and proper voltage output while the ignition is in the 'on' position. Additionally, it’s crucial to assess the glow plug's health, which should measure around 1.0-2.0 ohms of resistance when cold, as high resistance indicates failure. In colder climates, the glow plugs often fail after prolonged exposure to harsh conditions. A detailed check of the ignition system and battery voltage during cranking (ideally above 10.5V) should also be performed to rule out electrical issues contributing to the no-start condition.
Possible Causes
Most common causes (ordered by frequency):
- Glow Plug Relay Failure: The relay controlling the glow plugs may not be supplying adequate voltage due to corrosion or internal failure. Relay testing should confirm continuity and proper voltage output during the ignition cycle. A faulty relay typically leads to insufficient heat generation in the glow plugs, especially under cold conditions. - Intermittent starting issues, no glow plug activation, check engine light may be present.
- Glow Plug Malfunction: Individual glow plugs may have failed, leading to inadequate heating for cold starts. Each glow plug should measure around 1.0-2.0 ohms. High resistance indicates a malfunctioning plug. This is especially common in older diesel engines. - Poor cold start performance, visible damage to glow plugs, measuring resistance shows values outside of specification.
- Fuel Delivery System Issues: Although fuel is present at the injector line, the lift pump may not be providing sufficient pressure. A fuel pressure test should confirm delivery at 4-6 PSI. Any deficiencies could indicate a failing lift pump or clogged fuel filter. - Inconsistent fuel flow, pressure testing shows values below specifications.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Relay Testing: Begin by testing the glow plug relay for continuity and proper voltage output. Use a multimeter to check for voltage at the output terminal of the relay when the ignition is turned on. If no voltage is detected, the relay is likely faulty and should be replaced.
- STEP 2 - Glow Plug Resistance Check: Inspect each glow plug for resistance using a multimeter. Each plug should have a resistance reading between 1.0-2.0 ohms. Replace any plugs that measure significantly higher, indicating they are not functioning correctly.
- STEP 3 - Fuel Pressure Testing: Conduct a fuel pressure test at the injector line to ensure adequate fuel delivery. The pressure should be within the range of 4-6 PSI. If the pressure is insufficient, inspect the lift pump and fuel filter for blockages or failure.
- STEP 4 - Visual Inspection of Connections: Check all electrical connections related to the glow plug system and fuel delivery for corrosion or damage. Ensure tight connections to prevent intermittent issues caused by poor contact.
