P1A99 GMC Code - Starter/Generator Control Module Hybrid Battery Current Sensor Circuit Low Current
Quick Answer
The purpose of the Accessory Power Module (APM), integral to the Starter/Generator Control Module (SGCM), is to control the amount and direction of energy flowing between the 42 volts DC and 14 volts DC buses via the APM, bi-directional 42 volts DC to 14 volts DC converter. Common causes include Faulty Starter/Generator Control Module (SGCM), Starter/Generator Control Module (SGCM) harness is open or shorted, Starter/Generator Control Module (SGCM) circuit poor electrical connection. 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
- P1A99 GMC indicates Starter/Generator Control Module Hybrid Battery Current Sensor Circuit Low Current.
- Common causes
- Common causes include Faulty Starter/Generator Control Module (SGCM), Starter/Generator Control Module (SGCM) harness is open or shorted, Starter/Generator Control Module (SGCM) circuit poor electrical connection.
- 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 P1A99 GMC Description
The Starter/Generator Control Module (SGCM) controls 2 functions in these DTCs. DC voltage is transformed into three phase AC power to the electric machine interface. In this case, energy flows from 36 volt to phase1, phase2 and phase3. The second case shall be generating, where the three phase AC power is used to charge the 36 volt battery pack. In this case, energy flows from phase1, phase2 and phase3 to 36 volts.
What are the Possible Causes of the DTC P1A99 GMC?
- Faulty Starter/Generator Control Module (SGCM)
- Starter/Generator Control Module (SGCM) harness is open or shorted
- Starter/Generator Control Module (SGCM) circuit poor electrical connection
How to Fix the DTC P1A99 GMC?
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 P1A99 GMC 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 P1A99 GMC Code
1. What does the OBDII code P1A99 on a GMC vehicle mean?
The P1A99 code indicates an issue with the Starter/Generator Control Module detecting low current in the hybrid battery current sensor circuit.
2. What are the common symptoms of the P1A99 code in a GMC vehicle?
Symptoms may include the hybrid system warning light being illuminated, reduced fuel efficiency, limited hybrid system performance, or the vehicle entering limp mode.
3. What causes the P1A99 code to appear on a GMC vehicle?
Common causes include a faulty hybrid battery current sensor, damaged or corroded wiring, loose electrical connections, or a malfunctioning Starter/Generator Control Module.
4. How is the P1A99 code diagnosed in a GMC vehicle?
A technician will use a scan tool to read the code, inspect the hybrid battery current sensor and wiring, and test the voltage and continuity of the circuit to pinpoint the issue.
5. Can I drive my GMC vehicle with the P1A99 code?
While it may be possible to drive the vehicle, it is not recommended, as the hybrid system may not function properly and could lead to further damage or reduced performance.
6. How do you fix the P1A99 code on a GMC vehicle?
Repairs may involve replacing the hybrid battery current sensor, repairing or replacing damaged wiring, securing connections, or reprogramming or replacing the Starter/Generator Control Module if needed.
7. What tools are required to resolve the P1A99 code on a GMC vehicle?
You will typically need a diagnostic scan tool, a multimeter for testing electrical circuits, and basic tools for accessing and replacing components.
8. How much does it cost to fix the P1A99 code in a GMC vehicle?
Repair costs vary depending on the issue, ranging from $100 for simple wiring fixes to several hundred dollars for component replacements or module reprogramming.
9. Can a dead hybrid battery cause the P1A99 code?
While a dead hybrid battery could cause related issues, this code specifically points to a problem with the battery current sensor or its circuit, not the battery itself.
10. Is the P1A99 code unique to GMC hybrid vehicles?
Yes, the P1A99 code is typically found in GMC hybrid vehicles and relates specifically to the Starter/Generator Control Module and hybrid battery current sensor circuit.
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