Transmission Control System MIL Request Circuit Low
Code P0898 indicates that the transmission control module (TCM) has detected a low voltage condition on the malfunction indicator lamp (MIL) request circuit. This circuit is used by the TCM to signal the powertrain control module (PCM) to illuminate the check engine light. A low voltage reading suggests a short to ground, open circuit, or faulty component in the wiring or connectors between the TCM and PCM.
01. Most Common Causes
- Short to ground in the MIL request circuit wiring
- Open circuit or high resistance in the MIL request circuit
- Faulty transmission control module (TCM)
- Corroded or damaged connectors in the circuit
02. Symptoms You Will Notice
- Check engine light illuminated
- Transmission may not shift properly
- Reduced fuel economy
- Possible limp mode activation
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Visually inspect the wiring and connectors for the MIL request circuit for damage, corrosion, or loose connections.
Step 3: Measure voltage at the TCM connector on the MIL request circuit; compare to manufacturer specifications.
Step 4: Check for continuity and shorts to ground using a multimeter.
Step 5: If wiring is intact, suspect a faulty TCM and perform further module testing.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the transmission may enter limp mode, causing poor performance and potential damage. Have the vehicle inspected promptly.
How much does it cost to fix?▼
Repair costs typically range from $50 to $150 for wiring repairs or connector replacement. If the TCM needs replacement, costs can be higher.