B1566 Door Ajar Circuit Short To Ground

How to Diagnose and Solve B1566 Door Ajar Circuit Short To Ground Issues


If you’re experiencing issues with your car’s door ajar circuit, specifically the B1566 code, you’re not alone. This problem can be frustrating and even dangerous if left unresolved. Fortunately, with a little bit of knowledge and some DIY skills, you can diagnose and solve this issue on your own. In this article, we’ll walk you through the steps to diagnose and solve B1566 door ajar circuit short to ground issues.

What is the B1566 Code?

The B1566 code is a diagnostic trouble code (DTC) that indicates a short to ground in the door ajar circuit. This code is specific to Ford vehicles and is often accompanied by a warning light on the dashboard that indicates a door is open when it’s actually closed. This can be a safety hazard, as it can lead to the door opening unexpectedly while driving.

Diagnosing the Issue

The first step in diagnosing the B1566 code is to check the wiring and connections in the door ajar circuit. Start by inspecting the wiring harness and connectors for any signs of damage or corrosion. If you find any damage, repair or replace the affected parts.

Next, use a multimeter to test the resistance of the door ajar switch. The switch should have a resistance of around 10 ohms when closed and infinite resistance when open. If the resistance is outside of these ranges, replace the switch.

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If the wiring, connectors, and switch all check out, the issue may be with the body control module (BCM). Use a scan tool to check for any BCM trouble codes. If you find any, follow the manufacturer’s diagnostic procedures to resolve them.

Solving the Issue

Once you’ve identified the cause of the B1566 code, it’s time to solve the issue. If the problem was with the wiring, connectors, or switch, repair or replace the affected parts as necessary.

If the issue was with the BCM, you may need to replace it. However, before doing so, try resetting the BCM by disconnecting the battery for a few minutes. This can sometimes clear any stored trouble codes and resolve the issue.

Preventing Future Issues

To prevent future issues with the door ajar circuit, it’s important to keep the wiring and connectors in good condition. Check them regularly for signs of damage or corrosion and repair or replace them as necessary.

Additionally, be sure to close all doors properly to avoid putting unnecessary strain on the door ajar switch. Slamming doors can cause the switch to wear out more quickly, leading to more frequent issues.


Dealing with the B1566 code can be frustrating, but with the right knowledge and skills, you can diagnose and solve the issue on your own. By following the steps outlined in this article, you can get your car’s door ajar circuit back in working order and avoid any potential safety hazards.


1. Can I drive my car with the B1566 code?

While it’s technically possible to drive your car with the B1566 code, it’s not recommended. This code indicates a safety hazard, as it can lead to doors opening unexpectedly while driving. It’s best to resolve the issue before driving your car.

2. How much does it cost to fix the B1566 code?

The cost to fix the B1566 code will depend on the cause of the issue. If it’s a simple wiring or connector problem, it may only cost a few dollars to fix. If the issue is with the BCM, however, it could cost several hundred dollars to replace.

3. Can I fix the B1566 code myself?

Yes, it’s possible to diagnose and fix the B1566 code yourself if you have some DIY skills and the right tools. However, if you’re not comfortable working on your car’s electrical system, it’s best to take it to a professional mechanic.