Output Driver Module 4 Malfunction (Chevrolet)
What does P1670 mean?
The P1670 code means the vehicle's onboard diagnostic system has detected: Output Driver Module 4 Malfunction (Chevrolet). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Multiple output circuits not functioning
- Cooling fan inoperative
- Air conditioning not working
- Erratic engine accessory behavior
Probable Causes (Ranked by Likelihood)
- Internal PCM output driver failure Very High
- Shorted external load drawing excessive current High
- Water intrusion into PCM housing Moderate
- Poor PCM ground or power connection Low
Step-by-Step Diagnostic Procedure
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Use a scan tool to identify which specific outputs are assigned to driver module 4 on your vehicle.
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Check each output circuit for shorts to ground or excessive current draw.
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Inspect the PCM housing for signs of water intrusion, especially on models with cowl-mounted PCMs.
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Verify PCM power and ground circuits are within specification.
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If external circuits are all normal, the PCM internal output driver has likely failed and needs replacement.
Frequently Asked Questions
What is an output driver module?
The PCM contains internal transistor circuits called output driver modules that control external components like relays, solenoids, and indicators. Each module controls a group of outputs.
Can a shorted relay damage the PCM?
Yes. A shorted relay coil or seized relay can draw excessive current through the PCM output driver, eventually burning it out.
Should I get a new or remanufactured PCM?
Remanufactured PCMs from reputable suppliers are usually reliable and significantly less expensive. Ensure the replacement includes proper programming for your VIN.