Case IH 3042 – VCM: HS Power stage cold start heater relay - NO SIGNAL / Air filter: modeled air pressure drop is greater than measured

The ECU is not receiving a signal from the high-speed power stage cold start heater relay, or the system suspects the air filter is torn, missing, or there is a leak in the intake ducting.

• Steiger
• Magnum
• Axial-Flow combines

1. 1

   If diagnosing the air filter leak cause: Inspect the engine air filter housing for a missing filter element, and check the air filter pressure drop sensor and its wiring for faults.

2. 2

   If diagnosing the air filter leak cause: Inspect the ducting between the air filter and the engine/turbo intake for cracks, loose clamps, or rough surfaces that could allow unmetered air to bypass the filter.

3. 3

   If diagnosing the heater relay cause (official CNH 3042 definition): Check the HS Power stage cold start heater relay for a 'NO SIGNAL' condition. Verify battery voltage, relay connections, and the wiring harness.

1. 1

   Remove filters

   If addressing the air filter leak cause: Open the air cleaner housing and remove the primary and secondary air filters.

2. 2

   Inspect filter media

   If addressing the air filter leak cause: Inspect the filter media for holes, tears, or collapsed pleats.

3. 3

   Replace filters

   If addressing the air filter leak cause: If the filter is damaged or missing, replace both the primary and secondary air filters. Do not attempt to clean and reuse a damaged filter.

4. 4

   Secure intake ducting

   If addressing the air filter leak cause: Secure all intake ducting and tighten clamps to ensure no air bypasses the filter.

5. 5

   Test and replace relay

   If addressing the official CNH 3042 heater relay code: Locate the cold start heater relay, test for continuity, and replace the relay if it fails to send a signal to the ECU.

6. 6

   Clear fault codes

   Clear the fault codes using the EASy tool or a compatible CAN-bus diagnostic scanner.