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B1318RAMRAM 3500 HubAll RAM B1318Medium Severity

B1318 on RAM 3500

Battery Voltage Low

Factory diagnostic protocol and troubleshooting wire for fault code B1318 specifically for the RAM 3500 (2020–2026, 6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel)).

Verified OEM Telemetry & Field Repair Tree
RAM 35002020–2026
RAM 3500
Truck6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
3500 SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Drivable (Short Trip)
Medium urgency level
Est. Repair Cost
$80 - $250 (DIY: $0 - $180)
Parts & Labor DIY
Check B1318 On Another RAM Model:
Diagnose B1318 on Specific 3500 Model Year:

1. Symptoms of B1318 on RAM 3500

When the Engine Control Module (ECM/PCM) on your RAM 3500 (6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel)) logs fault code B1318, drivers commonly observe:

Battery warning light on dash on RAM 3500 (6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel))
Slow engine cranking or rapid clicking starter on RAM 3500 (6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel))
Random electrical accessories (radio, power windows) shutting off on RAM 3500 (6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel))
Multiple U-codes and B-codes stored simultaneously on RAM 3500 (6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel))
RAM 3500 OBD-II Port Location
The 16-pin diagnostic connector is located Driver lower kick panel near emergency brake assembly. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on RAM 3500

Historical warranty claims and technical repair bulletins for RAM 3500 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)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for RAM 3500.

3. Step-by-Step DIY Repair Guide for RAM 3500

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 the RAM 3500 equipped with 6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel).

Required Tool: Digital Multimeter
02
Clean Battery Posts and Terminals

Remove corrosion with baking soda solution and wire brush, tighten terminal clamps firmly. on the RAM 3500 equipped with 6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel).

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 the RAM 3500 equipped with 6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel).

Required Tool: Multimeter
04
Replace Battery or Alternator as Indicated

Install new high-CCA AGM or flooded battery, or replace alternator. on the RAM 3500 equipped with 6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel).

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

Clear DTCs and perform Battery Management System (BMS) reset if equipped. on the RAM 3500 equipped with 6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel).

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

Equipment for Diagnosing RAM 3500 (B1318)

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RAM 3500 OEM Replacement Sensor

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Direct-fit replacement assembly engineered to OEM tolerances for RAM 3500.

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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
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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.

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Other Common Fault Codes on RAM 3500

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the RAM 3500:

4. RAM 3500 B1318 FAQs

What causes code B1318 to trigger on a RAM 3500?

On the RAM 3500 (6.7L High-Output Cummins Turbo-Diesel (420HP / 1,075 lb-ft torque / Dual Rear Wheel)), B1318 is most frequently caused by Failing 12V automotive battery (sulfated plates or dead cell) or Faulty alternator not charging battery (>13.5V).

Where is the OBD-II port located on my RAM 3500?

On the RAM 3500, the 16-pin DLC diagnostic connector is located Driver lower kick panel near emergency brake assembly. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my RAM 3500 with code B1318?

Caution. Low voltage (<10V) causes random module dropouts, flickering dash lights, and stalling. Given that B1318 carries a Medium severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.