B1302 — Accessory Delay Relay Coil Circuit Failure #

Note: The description for code B1302 may vary depending on the vehicle manufacturer (OEM). Please refer to your specific service manual for exact terminology.

• Accessory Delay Relay Coil Circuit Failure (Ford, Lincoln, Mercury)
• Accessory Delay Relay Circuit Malfunction (GM, Chevrolet)
• Accessory Power Relay Coil Circuit Error (Chrysler, Dodge)

Summary of code B1302 #

The B1302 code indicates a problem detected by the vehicle’s Body Control Module (BCM) in the accessory delay relay coil circuit. This relay controls the power supply to accessories such as the radio, windows, and sunroof, allowing them to function for a short period after the ignition is turned off. When this circuit fails, the BCM is unable to manage accessory power timing as intended. The root of this code is typically electrical: a break in the coil circuit, poor relay connections, or a failed relay itself. Left unchecked, this issue can lead to inconvenience or even more severe electrical problems in the vehicle’s accessory systems.

Common symptoms for code B1302 #

Drivers and technicians might notice several telltale signs when the accessory delay relay coil circuit malfunctions. These symptoms can range from subtle inconveniences to more noticeable electrical quirks. Here’s what you may experience:

• Power windows, radio, or sunroof stop working immediately when the ignition is turned off
• Accessory features do not stay powered for the usual delay period after key-off
• Accessory functions may not work at all
• Intermittent loss of accessory power
• Occasional flickering of interior lights or displays
• BCM or “Body Control Module” warning light (if equipped)

Probable causes for code B1302 #

The most frequent reasons for a B1302 code are typically electrical in nature. Diagnosing the precise cause requires a stepwise approach, but statistically, these are the most common culprits:

1. Faulty accessory delay relay: The relay itself may have an internal coil failure or poor contacts.
2. Open or short in the relay coil circuit wiring: Broken wires, corroded connectors, or pinched harnesses are classic troublemakers.
3. Poor relay socket connection: Loose, corroded, or bent pins where the relay plugs in can lead to intermittent or complete failure.
4. Faulty BCM (Body Control Module): Rare, but possible if the module cannot control the relay circuit.
5. Blown fuse or improper fuse rating: A blown or incorrect accessory fuse can disrupt relay operation.

Step-by-step diagnosis for code B1302 #

Diagnosing a B1302 code is a logical process, similar to following breadcrumbs through a forest. Use a quality multimeter and follow these steps:

• 1. Scan for other codes: Check for related BCM or electrical fault codes that could offer clues.
• 2. Inspect the accessory delay relay: Remove and visually inspect the relay for signs of corrosion, burning, or damage.
• 3. Test relay operation: Swap with a known-good relay (if available) or bench-test the relay for continuity and coil resistance.
• 4. Inspect relay socket and wiring: Look for loose, corroded, or damaged wires and connectors at the relay socket.
• 5. Check circuit continuity: With the relay removed, use a multimeter to test for continuity between the relay’s coil terminals and the BCM. Repair any open or shorted circuits.
• 6. Test accessory function: With a new or known-good relay, confirm if accessory delay now works post-ignition.
• 7. BCM test (if necessary): If all else checks out, use OEM-specific scan tools to test the BCM’s relay control output. Replace the module if confirmed faulty.

Possible repairs for code B1302 #

Repairing the B1302 code usually involves addressing the root cause found during diagnosis. Here’s what may be required:

• Replace the accessory delay relay if internal failure or poor contacts are found.
• Repair or replace damaged wiring in the relay coil circuit (including connectors and sockets).
• Clean or replace corroded relay sockets to restore solid electrical contact.
• Replace the Body Control Module (BCM) only if all wiring and relays test good and the module fails OEM diagnostic checks.
• Replace blown or incorrect fuses with the proper OEM-specified ratings.

Is it safe to drive with code B1302? #

Limited use is possible, but not recommended for the long term. The B1302 code does not typically affect the engine or vehicle safety systems. However, the loss of accessory power can be inconvenient and may cause further electrical issues if ignored. For example, losing window or sunroof control could be problematic in adverse weather or during emergencies. Prompt repair is advised to avoid compounding problems.

Vehicles most commonly affected by code B1302 #

While B1302 is a generic OBD-II code, it appears more frequently in certain makes and models where accessory delay relays are a known weak point. The following vehicles are commonly reported by technicians and owners:

• Ford F-Series (F-150, F-250, etc.)
• Ford Explorer, Expedition, and Taurus
• Lincoln Navigator, Town Car
• Mercury Grand Marquis
• Chevrolet Silverado
• Chevrolet Tahoe, Suburban
• Chrysler Town & Country
• Dodge Grand Caravan

Common mistakes & best practices for code B1302 #

Even seasoned technicians can be tripped up by this code. Avoid these pitfalls to ensure a clear diagnosis and repair:

• Replacing the relay without testing: Always confirm relay failure before replacement, as wiring or socket faults are equally common.
• Ignoring corroded connectors: Surface corrosion or loose pins can cause intermittent failures that mimic relay or BCM faults.
• Overlooking related fuses: Fuses protect the circuit—never skip checking them for the correct rating and condition.
• Skipping a scan for other codes: Related BCM or U-codes may point to a deeper network or module issue.
• Not using OEM wiring diagrams: Always reference diagrams specific to your vehicle; wire colors and pinouts can differ by model/year.

Quick FAQ for code B1302 #

Got a question about B1302? Here are answers to what owners and techs ask most:

Q: Can I just pull the relay to “reset” the code?
A: Removing and reinstalling the relay may temporarily clear the code if contact corrosion is minor, but the underlying problem will return unless properly fixed.

Q: Will a faulty accessory delay relay drain my battery?
A: Typically, no. In most cases, the circuit fails “open” (accessories shut off immediately), but a stuck relay could potentially allow accessories to stay powered, risking battery drain. Always confirm proper operation after repairs.