Episode April 27, 2025 11 min 44s

Call Of The Week - Ron Ananian, The Car Doctor - Hour 2 - April 26, 2025 - Eric in PA, 2013 Chevy Suburban, Engine Dies, Limp Mode, Since Engine Replacement

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Here's a summary and bullet point breakdown of the call between Eric from Pennsylvania and Ron Ananian on The Car Doctor radio show from April 26, 2025:

🔧 Caller Issue:

Vehicle: 2013 Chevrolet Suburban LTZ
Mileage: 230,000 miles
Engine: Multiple crate engine replacements (current one is 3rd crate engine)
Main Symptom:
- Voltage drops from ~14V to 10V during driving, especially on long trips.
- AC compressor shuts off when voltage drops.
- Vehicle eventually enters limp mode.
- Turning headlights on brings voltage back to normal (~14V).

🛠️ Previous Work Done:

New Alternator and Battery: Both replaced with OEM GM parts (twice).
Added Ground Wires: Installed by an electrical specialist.
AFM (Active Fuel Management) Disabled.
No Aftermarket Parts: Only modification is AFM delete.

🧠 Diagnostic Observations & Suggestions (Ron Ananian):

Key Question: Is this a headlight-specific circuit issue or a general electrical load problem?
Blower Fan Test:
- Blower fan doesn’t resolve the issue like headlights do, suggesting it’s circuit-specific, not general load.
Electrical Theory:
- Turning headlights on might bypass GM’s energy-saving mode, stabilizing voltage.
- Could be a module communication/network issue—one module dropping out could cause system-wide failure.
- Ron compares it to computers on a network: one fails, the rest follow.

🧪 Further Diagnostic Path Ron Suggests:

Scan Tool Needed: Check for module communication failures during voltage drop.
Cluster/Oil Pressure Warning:
- Oil pressure reads low on dash but is fine on manual gauge.
- Possible faulty cluster or wiring issue, possibly affecting system behavior.
Check Bulkhead Connector: Wiring harness going through firewall may be suspect.
Evaluate What’s Working: Don’t just chase bad parts—establish what’s good (e.g., fuel trims, throttle position, vacuum).
Disconnect AC Compressor Electrically:
- See if the issue still occurs with AC unplugged to isolate AC clutch as a cause.

🔁 Next Steps for Eric:

Determine if AC compressor clutch is affecting the system or just coincidentally shutting off.
Investigate further with his technician using Ron’s suggestions.
Call back with updates for continued guidance.

Full episodes of Ron Ananian, The Car Doctor also available.

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