SCP Bus Communication Failure with Cassette Module
The U1166 code indicates a communication fault on the SCP (Standard Corporate Protocol) data bus, specifically involving invalid or missing data from the cassette module. SCP is a Ford proprietary network operating at 41.6 kbps using pulse-width modulation (PWM) on a single wire. This code is set when a control module (typically the PCM, instrument cluster, or audio module) detects that expected data from the cassette module is absent, corrupted, or does not conform to valid SCP message format. The cassette module is part of the entertainment system and, while not critical for vehicle operation, its integration into the data bus can affect diagnostics and network functions.
1. Commonly Affected Makes
2. Most Common Causes
- Failed cassette or integrated CD player module
- Open or short circuit in SCP bus wiring (circuits 914 and/or 915)
- Incorrect SCP bus termination resistance (should be approximately 120 ohms)
- Faulty master control module (GEM, instrument cluster, or PCM depending on configuration)
- Poor connection at the audio/cassette module connector
- Electromagnetic interference corrupting SCP messages
- Outdated or corrupted audio module software
3. Symptoms You Will Notice
- Cassette player or CD player inoperative
- Audio system may not function or display errors
- Possible communication issues with other modules on the SCP bus
- Check Engine Light or other warning lights may illuminate
4. Step-by-Step Diagnosis
Scan for all stored codes and note any related communication codes
Inspect SCP bus wiring (circuits 914 and 915) for damage, corrosion, or shorts
Measure bus termination resistance at the data link connector; should be about 120 ohms
Check cassette module connector for bent pins, corrosion, or poor contact
Test cassette module by substitution if possible
Verify software version of audio module and update if necessary
If bus wiring and termination are good, suspect master control module (GEM, cluster, or PCM)
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is safe to drive. The cassette module is part of the entertainment system and does not affect engine or safety systems. However, other communication issues may arise on the SCP bus.
How much does it cost to fix?▼
Repair costs vary widely. Diagnosing and repairing wiring issues can range from $100 to $300. Replacing a cassette module may cost $150 to $400, while a master control module replacement can be $500 to $1,200 including labor.