P1890 — Transmission 4WD Mode Select Return Input Circuit Failure

What Does P1890 Mean?

P1890 is a manufacturer-specific diagnostic trouble code: Transmission 4WD Mode Select Return Input Circuit Failure. This code applies to OTHER, BUICK, CADILLAC, CHEVY, GM vehicles. Unlike generic OBD-II codes, manufacturer-specific codes are defined by the vehicle maker and may only apply to certain makes and models.

Symptoms of P1890

⚠️ Check Engine Light (MIL) illuminated
⚠️ Erratic Transmission 4WD Mode Select Return Input readings
⚠️ Related system operating intermittently
⚠️ Reduced engine performance

Common Causes

🔍 Wiring issue in Transmission 4WD Mode Select Return Input circuit (damaged, chafed, or corroded)
🔍 Faulty Transmission 4WD Mode Select Return Input connector or terminal
🔍 Failed Transmission 4WD Mode Select Return Input
🔍 ECM/PCM connection issue

Frequently Asked Questions

What does P1890 mean?

P1890 indicates: Transmission 4WD Mode Select Return Input Circuit Failure. The vehicle's computer has detected that the Transmission 4WD Mode Select Return Input is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1890?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1890 for extended periods may cause additional problems.

How much does it cost to fix P1890?

Repair costs for P1890 typically range from $80 to $300, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Inspect and repair Transmission 4WD Mode Select Return Input wiring and connectors
🔧 Replace faulty Transmission 4WD Mode Select Return Input

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

P1890: Transmission 4WD Mode Select Return Input Circuit Failure