U0120 Lincoln Code - Lost Communication With Starter/Generator Control Module
Quick Answer
The alternator is controlled by the Power Control Module (PCM) which monitors certain parameters such as the engine temperature, battery temperature and electrical demand. Common causes include Faulty Starter Motor, Faulty Generator/Alternator, Starter Motor harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- U0120 Lincoln indicates Lost Communication With Starter/Generator Control Module.
- Common causes
- Common causes include Faulty Starter Motor, Faulty Generator/Alternator, Starter Motor harness is open or shorted.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code U0120 Lincoln Description
- The first thing to check is if the battery is the correct type. Smart charge systems are designed to be used only with a silver calcium battery not the lead acid type due to the voltages used which may damage a lead acid battery and give incorrect readings.
- If you disconnect the 3 pin PCM plug from the alternator and it is charging again, this will show the alternator is being controlled by the PCM. This will check if the alternator is still functioning. The 3 pin plug will need to be reconnected immediately after the test to avoid any damage to the vehicle. This test is a temporary check only and is not a resolution to the fault. Disconnection and reconnection of the 3 pin plug should be done when the engine is switched off.
If the battery is of the correct type and the alternator is found to be charging, the next part to check is the continuity of the wiring loom from the alternator to the PCM. Due to the location of the alternator in relation to the PCM, the wiring can become chafed or the insulation melts from being too close to a heat source. This is a common reason when the battery light is illuminated and a new loom will be needed.
What are the Possible Causes of the DTC U0120 Lincoln?
- Faulty Starter Motor
- Faulty Generator/Alternator
- Starter Motor harness is open or shorted
- Starter Motor circuit poor electrical connection
- Generator/Alternator harness is open or shorted
- Generator/Alternator circuit poor electrical connection
How to Fix the DTC U0120 Lincoln?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the U0120 Lincoln code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about U0120 Lincoln Code
1. What does the OBDII code U0120 mean on a Lincoln vehicle?
The U0120 code means the vehicle has lost communication with the Starter/Generator Control Module, which is responsible for managing the starter and generator functions.
2. What are the common symptoms of the U0120 code?
Symptoms may include the engine not starting, intermittent starting issues, a no-crank condition, or warning lights on the dashboard like the check engine light.
3. What causes the U0120 code to appear?
Common causes include a faulty Starter/Generator Control Module, damaged wiring or connectors, a dead battery, or communication issues in the CAN (Controller Area Network) bus.
4. Can a weak battery cause the U0120 code?
Yes, a weak or discharged battery can interrupt communication between the control modules and trigger the U0120 code.
5. How do I diagnose the U0120 code?
Diagnosis involves checking the battery voltage, inspecting wiring and connectors for damage or corrosion, and using a scan tool to test communication on the CAN network.
6. Is it safe to drive with the U0120 code?
It’s not recommended to drive with this code as it can lead to starting failures or other electrical issues, potentially leaving you stranded.
7. How can I fix the U0120 code on my Lincoln?
Repairs may involve replacing or reprogramming the Starter/Generator Control Module, repairing damaged wiring, or ensuring secure and clean connections.
8. How much does it cost to repair the U0120 code?
Repair costs can vary but generally range from $100 to $1,000 depending on whether the issue is a simple wiring repair or module replacement.
9. Can a software update fix the U0120 code?
Yes, in some cases, a software update or reprogramming of the Starter/Generator Control Module can resolve the issue.
10. What tools are needed to troubleshoot the U0120 code?
You’ll need an OBDII scan tool with CAN bus diagnostics, a multimeter for electrical tests, and possibly a repair manual for your specific Lincoln model.
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