C1597 on 2019-2022 GMC Sierra 1500: Power Steering Failure, Grounding Issues, and Fixes

What's Unique About the 2019-2022 Gmc SIERRA 1500

The T1 platform, which includes the 2019-2022 Sierra 1500, is known for being sensitive to electrical ground issues that directly impact the electric power steering system. GM has issued multiple Technical Service Bulletins (TSBs), most notably PIT6088 and 23-NA-201, specifically pointing to poor main ground connections as the likely cause for power steering failures that trigger code C1597. TSB 23-NA-201 specifically identifies grounds G132 (Engine) and G133 (Frame) located behind the right-hand (passenger side) wheelhouse liner as a primary failure point due to corrosion and high resistance. Unlike many other vehicles where a steering code might immediately point to a module or rack failure, on these trucks, the first and most critical diagnostic step is to verify the integrity of these specific ground points.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Complete loss of power steering assist, making the steering wheel very hard to turn.
• "Service Power Steering" message on the driver information center (DIC).
• "Steering Assist is Reduced Drive With Care" message on the 🎬 See how to troubleshoot the Steering Assist is Reduced warning. DIC.
• Other warning lights, such as for the ESC (Electronic Stability Control) or brake system, may illuminate at the same time.
• Intermittent loss of power steering that may temporarily resolve after turning the vehicle off and on again.
• Grinding or whining sounds when turning the steering wheel.

Most Likely Causes

1. Poor or Corroded Main Ground Connections (G132 & G133) 🔴 High Probability GM TSBs PIT6088 and 23-NA-201 identify poor grounds as the primary cause. TSB 23-NA-201 specifically calls out high resistance in G132 (Engine) and G133 (Frame) grounds, which are located behind the front right-hand wheelhouse liner, exposing them to road salt and moisture that accelerates corrosion. Owners report the braided straps can become completely 'dissolved'.
   How to confirm: Visually inspect and physically check the ground straps, especially G132 and G133 behind the front passenger wheel well liner. TSB PIT6088 advises inspecting G130, G131, G132, G133, and G134. Look for green or white corrosion, looseness, or fraying of the braided cable. Lightly pull on the ground straps to ensure they do not break and the eyelets are secure.
   Typical fix: Disconnect the ground connection, thoroughly clean the contact surfaces of the terminal and the frame/engine block down to bare metal, and securely re-tighten the connection. If a braided strap is corroded, frayed, or broken, it must be replaced. Many owners opt for a more robust, shielded wire instead of a braided strap.
   Est. part cost: $10-$60
2. Failing Vehicle Battery 🟡 Medium Probability → Shop Vehicle Battery The electric power steering system draws significant current. A weak or failing battery can cause voltage drops during high-load situations (like turning at a standstill), which can trigger faults in sensitive modules like the PSCM. In some cases, simply replacing a dead battery can leave a 'current' fault code in the PSCM that won't clear without a dealer tool, mimicking a more serious issue.
   How to confirm: Have the battery professionally tested using a carbon pile load tester. A simple voltage check with a multimeter is often not sufficient to identify a weak battery that fails under load. TSB 18-NA-161 recommends performing a loaded voltage drop test on the main battery cables; voltage drop should not exceed 200 mV on the negative cable or 100 mV on the positive cable during a steady crank.
   Typical fix: Replace the vehicle's 12V battery.
   Est. part cost: $150-$350
3. Power Steering Control Module (PSCM) Software Error ⚪ Low Probability → Shop Power Steering Control Module GM TSB 20-NA-113 identifies a calibration error where a temporary fault (often from a low voltage event like a dead battery) can cause a DTC to remain 'current' instead of moving to 'history' after the issue is resolved. This keeps the warning message active on every startup even though no active fault exists.
   How to confirm: If all grounds and the battery are confirmed good, and the code persists, this is the next logical step. This requires a GM-specific scan tool (GDS2) to check the software calibration level and see if the code can be cleared. If it cannot be cleared but no physical fault is present, a reprogram is needed.
   Typical fix: A GM dealership or qualified shop must reprogram the PSCM with the latest software calibration using the TIS2Web service.
   Est. part cost: $0 (if under warranty) - $250

Rare But Worth Checking

• Damaged Wiring Harness: Some owners have reported the wiring harness near the steering components can rub and wear through, causing shorts. This is less common than a bad ground but can produce similar electrical symptoms. This should be inspected after grounds are confirmed good. TSB 23-NA-102 notes a potential for the engine wiring harness to contact the alternator bracket, causing various electrical issues.
• Faulty Power Steering Control Module (PSCM) or Rack Assembly: → Shop Power Steering Control Module While possible, outright failure of the PSCM or the entire steering rack is the least common cause for this specific code on this platform. This should only be considered an expensive last resort after all other electrical causes (grounds, battery, software, wiring) have been exhaustively ruled out.

Diagnosis Steps

1. Scan all modules for diagnostic trouble codes. Note all current and history codes, especially in the PSCM, EBCM, and BCM.
2. Begin by following GM TSB 23-NA-201: Inspect grounds G132 (Engine) and G133 (Frame). These are located behind the front right-hand (passenger side) wheelhouse liner. This is the most common point of failure.
3. Disconnect, thoroughly clean all contact points to bare metal, and securely retighten G132 and G133. If the braided straps are frayed or corroded, replace them.
4. Continue by inspecting the other grounds identified in TSB PIT6088: G130 (Battery Negative to Body), G131 (Frame), and G134 (Engine). Clean and tighten as needed.
5. If grounds are confirmed good, have the 12V battery professionally load tested. A weak battery is the next most likely cause. Per TSB 18-NA-161, perform a loaded voltage drop test on the main battery cables to check for high resistance.
6. If grounds and battery are good, attempt to clear the codes. If the C1597 code returns immediately and cannot be cleared, suspect a software issue per TSB 20-NA-113. The PSCM will likely need to be reprogrammed by a dealer.
7. If the code still persists after software has been ruled out, perform a detailed inspection of the wiring harness leading to the power steering rack for any signs of chafing, rubbing, or physical damage, paying attention to the area near the alternator bracket as noted in TSB 23-NA-102.
8. As a final step, if all grounds, battery, software, and wiring are confirmed to be in perfect condition, diagnosis would point towards an internal failure of the power steering rack and pinion assembly, which includes the integrated PSCM.

Parts You'll Likely Need

• Braided Ground Strap/Cable (OEM #84827778) — The ground straps, especially G132 and G133, are prone to corrosion and breakage, which is the most common cause of code C1597. Part number 84827778 is listed for this application.
  Trusted brands: ACDelco (GM Genuine), Dorman
  OEM price range: $25-$60
  Aftermarket price range: $10-$30
• Battery — A weak battery is a common cause of voltage-related faults in the electric power steering system.
  Trusted brands: ACDelco, Interstate, DieHard
  OEM price range: $200-$350
  Aftermarket price range: $150-$250

Related Codes That Often Appear With This One

• C1599 — This code is also related to a Power Steering Control Module fault and is often set alongside C1597, as noted in TSB PIT6088.
• P25A2 — This code for the Brake System Control Module is mentioned in both TSB PIT6088 and 23-NA-201 as potentially appearing with C1597 due to the shared electrical ground issues affecting both steering and brake assist.
• U0420 — This is a communication code indicating 'Invalid Data Received From Power Steering Control Module'. It can be triggered when the PSCM is malfunctioning or has an unstable power supply. It is also listed in TSB 23-NA-201.
• U0422 — Indicates 'Invalid Data Received From Body Control Module'. This code is also listed in TSB 23-NA-201 as appearing with steering/brake assist loss due to bad grounds.
• C116C — Another related code mentioned in TSB 23-NA-201 that can be set due to the high-resistance ground issue.

Technical Service Bulletins (TSBs) & Recalls

• PIT6088: Diagnostic tip for lack of power steering assist with DTCs C1597 and/or C1599. Instructs technicians to inspect main ground connections G130, G131, G132, G133, and G134 for integrity and tightness.
• 23-NA-201: Addresses loss of steering/brake assist due to high resistance in G132 and G133 grounds, located behind the RH wheelhouse liner. Lists multiple associated DTCs.
• 20-NA-113: Describes a PSCM calibration error that can keep DTCs 'current' after a temporary fault (like a battery replacement) is resolved, requiring a software update to fix the persistent dash warning.

Platform-Specific Known Issues

• GM Technical Service Bulletin PIT6088 directly addresses C1597 and a lack of power steering assist, pointing technicians to inspect five main ground connections first and providing a diagram.
• GM Technical Service Bulletin 23-NA-201 is more specific, identifying high resistance in grounds G132 and G133 (behind the RH wheelhouse liner) as a primary cause for loss of steering and brake assist, and lists several related DTCs that may appear simultaneously.

Mechanic-Grade Diagnostic Values

• Loaded voltage drop test on short positive battery cable — expected: Below 100 mV. Failure: A reading above 100 mV indicates high resistance in the cable, which should be replaced.
• Loaded voltage drop test on negative battery cable — expected: Below 200 mV. Failure: A reading above 200 mV indicates high resistance in the cable or its connections, which should be repaired or replaced.
• Battery cable clamp nut torque — expected: 7 Nm (62 lb in). Failure: Loose clamps can cause intermittent power loss to modules.
• Ground bolt torque (for specific grounds like G101, G102, etc.) — expected: 9 Nm (80 lb in). Failure: Improperly torqued ground bolts can lead to high resistance.

Scan Tool Commands That Help

• GDS2 (GM Techline Connect/TIS2Web): Power Steering Control Module - Prepare Control Module for Removal — This function must be used BEFORE removing the old Power Steering Control Module (PSCM) or assist motor. It saves critical data, like the worm gear wear counter, to the scan tool. This data is then written to the new module after installation.
• GDS2 (GM Techline Connect/TIS2Web): Power Steering Control Module - Programming — This function is used to flash the new PSCM or steering rack with the correct vehicle-specific software after it has been physically installed.
• GDS2 (GM Techline Connect/TIS2Web): Power Steering Control Module - Setup — After programming, this function performs necessary calibrations. This may include sub-functions like Power Steering Torque Sensor Learn, Software Endstop Learn, and Steering Angle Sensor Centering to complete the installation.

Wiring & Ground Locations

• G132 — Engine ground strap, located behind the front right-hand (passenger side) wheelhouse liner. Connects engine to body.. Specifically identified in TSBs PIT6088 and 23-NA-201 as a primary point of failure due to high resistance from corrosion, directly causing loss of power steering assist and code C1597.
• G133 — Frame ground strap, located behind the front right-hand (passenger side) wheelhouse liner.. Paired with G132 in TSB 23-NA-201 as a critical ground to inspect for high resistance causing steering and brake assist failures.
• G134 — Engine ground strap, also part of the main grounding scheme.. Listed in TSB PIT6088 as a key ground to inspect for integrity when diagnosing C1597.
• G131 — Frame ground strap.. Listed in TSB PIT6088 as a key ground to inspect for integrity when diagnosing C1597.
• G130 — Battery negative cable connection at the body.. Listed in TSB PIT6088 as a key ground to inspect for integrity when diagnosing C1597.
• K43 Power Steering Control Module — Integrated into the power steering rack and motor assembly.. This is the module setting the code. Its main power and data connectors (X1, X2) receive voltage and communication signals that are disrupted by bad grounds.

Real Owner Repair Stories

• Reddit user jmoney12360 on r/gmcsierra (2022 GMC Sierra 1500 3.0L Duramax, ~60,000 miles) — Steering locked straight on cold mornings (single-digit temperatures). Would eventually "break loose" after warming up and driving back and forth.
  ❌ Tried (didn't work) The dealer initially followed a TSB and replaced the ground straps, but this did not fix the issue.
  ✅ What actually fixed it The dealer determined the Electric Steering Gear Assembly needed to be replaced. The owner reported that GM covered half the cost under a "dealer empowerment program" and proceeded with the repair. Another user suggested water intrusion into the steering assembly could cause this, requiring replacement.

OEM Part Supersession History

• 23390040 → 84827778 — Standard part update/revision.
  Heads up: The new part number (84827778) is the correct replacement for the original and is specified for the 2019-2022 model years.

Model Year Variations Within This Range

• 2022: The 2022 model year was a split/refresh year. There is the 2022 "LTD" or "Limited" (RPO J21), which is a carryover of the pre-refresh design, and the "New" 2022 model (RPO J22) with the updated interior and exterior. TSBs like PIT6088 and 23-NA-201 explicitly list both versions, indicating the ground strap issue is present on both pre-refresh and post-refresh 2022 trucks.