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B1318 on RAM: Symptoms, Causes & Fix

Battery Voltage Low

Official technical diagnostic wire for fault code B1318 specifically affecting RAM vehicles (1500, 2500, 3500, TRX).

Sensor Voltage Ref
0.1V – 5.0V Ref
RAM Factory Standard
CAN Bus Speed
500 kbps CAN-FD
ISO 15765-4 Diagnostic Bus
Drivability Status
Drivable (Short Trip)
Medium urgency level
Est. Repair Cost
$80 - $250 (DIY: $0 - $180)
Parts & Labor DIY
Model-Specific Diagnostic Wires

Select Your RAM Model for B1318:

5 Models Available
RAM 15002020–2026
RAM 1500Truck • 3.0L Hurricane Twin-Turbo I6 (420HP/540HP) / 5.7L HEMI V8 eTorque / 3.6L Pentastar
B1318 Fix & DLC Location
RAM 25002020–2026
RAM 2500Truck • 6.7L Cummins Turbo-Diesel I6 (420HP / 1,075 lb-ft) / 6.4L HEMI V8 (410HP)
B1318 Fix & DLC Location
RAM ProMaster2020–2026
RAM ProMasterVan • 3.6L Pentastar V6 (280HP) / 3.0L EcoDiesel (174HP)
B1318 Fix & DLC Location
RAM 35002020–2026
RAM 3500Truck • 6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel)
B1318 Fix & DLC Location
RAM 1500 TRX2021–2024
RAM 1500 TRXTruck • 6.2L Supercharged HEMI V8 (702HP / 650 lb-ft / Bilstein Black Hawk e2)
B1318 Fix & DLC Location

1. Common Symptoms on RAM Vehicles

When RAM Engine Control Modules (ECM) trigger fault code B1318, drivers typically report:

Battery warning light on dash on RAM Powertrains
Slow engine cranking or rapid clicking starter on RAM Powertrains
Random electrical accessories (radio, power windows) shutting off on RAM Powertrains
Multiple U-codes and B-codes stored simultaneously on RAM Powertrains

2. Root Causes on RAM Engines

Historical diagnostic claims across RAM engines point to the following failure distribution:

55%
Failing 12V automotive battery (sulfated plates or dead cell) (RAM OEM Part)
25%
Faulty alternator not charging battery (>13.5V) (RAM OEM Part)
12%
Corroded or loose battery cable terminals (RAM OEM Part)
8%
Parasitic battery drain drawing power while parked (RAM OEM Part)

3. Step-by-Step Fix Protocol for RAM

01
Test Battery Open-Circuit Voltage

Measure resting battery voltage with engine off. Normal is 12.6V. If under 12.0V, battery is discharged. on RAM engines.

Required Tool: Digital Multimeter
02
Clean Battery Posts and Terminals

Remove corrosion with baking soda solution and wire brush, tighten terminal clamps firmly. on RAM engines.

Required Tool: Terminal Cleaning Brush, 10mm Wrench
03
Test Alternator Charging Voltage

Start engine and measure voltage across battery. Normal charging voltage is 13.8V to 14.6V. If below 13.0V, alternator has failed. on RAM engines.

Required Tool: Multimeter
04
Replace Battery or Alternator as Indicated

Install new high-CCA AGM or flooded battery, or replace alternator. on RAM engines.

Required Tool: Socket Set, Wrenches
05
Clear Trouble Codes & Reset BMS

Clear DTCs and perform Battery Management System (BMS) reset if equipped. on RAM engines.

Required Tool: OBD-II Scan Tool
Recommended Parts & Testing Tools

Equipment for Diagnosing RAM (B1318)

Prime Fast Delivery & Verified Fitment
Direct-Fit Replacement Part

RAM OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

Direct-fit replacement assembly engineered to OEM tolerances for RAM.

$45 – $95 Prime
Check Fitment on Amazon
Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

4.6 / 5.0 (Best Seller)

Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.

$29.99 Prime
View on Amazon
Top Mobile OBD-II Scanner

BlueDriver Bluetooth Pro OBDII Scan Tool

4.7 / 5.0 (50,000+ Reviews)

Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.

Compare OEM & Aftermarket Replacement Sensors for RAMVerified direct-fit pricing from Denso, Bosch, Motorcraft, and ACDelco on Amazon.
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4. RAM B1318 Frequently Asked Questions

What does code B1318 mean on a RAM?

On RAM vehicles, B1318 indicates that the Engine Control Module (ECM) detected battery voltage low. This typically points to Failing 12V automotive battery (sulfated plates or dead cell) or Faulty alternator not charging battery (>13.5V).

Can I continue driving my RAM with code B1318?

Caution. Low voltage (<10V) causes random module dropouts, flickering dash lights, and stalling. Because this code carries a Medium severity rating on RAM powertrains, we recommend scanning live data values promptly to prevent secondary damage.

How much does it cost to fix code B1318 on a RAM?

Estimated DIY parts cost ranges from $80 - $250 (DIY: $0 - $180), while professional shop repairs at an authorized RAM dealership or independent specialist typically range from $180 to $380 including diagnostic labor.