Openai/69416939-f2c4-8006-8547-74f228e826f2

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gpt-5-2

User: passat b5.5 avf 1.9tdi, automatic to manual swap - cruise control doesnt work after switching to manual

passat b5.5 avf 1.9tdi, automatic to manual swap - cruise control doesnt work after switching to manual

Assistant: On a Passat B5.5 AVF 1.9 TDI converted from automatic → manual, cruise control almost always fails due to coding and cl…

On a Passat B5.5 AVF 1.9 TDI converted from automatic → manual, cruise control almost always fails due to coding and clutch/brake input issues. The system is simple but strict.

What must be correct for cruise to work

1. ECU coding still set to AUTOMATIC (most common cause)

After the swap, the engine ECU must be recoded for manual transmission.

Fix

• VCDS → 01 Engine
• Coding
• Change transmission bit from automatic → manual
• Save and cycle ignition

If this is not done, cruise will never engage.

2. Clutch switch missing or wired incorrectly

Manual cars require two clutch-related inputs:

| Switch | Function | Required | | ----------------------------- | ------------------ | --------- | | Clutch pedal switch (F36) | Cruise cancel | YES | | Clutch position switch (F194) | Idle & start logic | Often YES |

Cruise will not work if ECU never sees “clutch released.”

Check

• VCDS → 01 Engine → Measuring Blocks
• Look for Clutch Pedal status
• Must change from Pressed → Released

Wiring (AVF ECU – common)

• One clutch switch pin → ECU clutch input
• Other pin → ground or 12V (depends on switch type)

If no clutch switch is fitted, cruise will be permanently disabled.

3. Brake light switch incorrect (needs 4-pin version)

Auto → manual swaps often keep the wrong brake switch.

Correct brake switch

• 4-pin brake light switch
• One circuit for brake lights
• One circuit for ECU/cruise

Symptoms of wrong switch

• Cruise won’t set
• Brake lights may still work normally

Check in VCDS

• Measuring blocks → Brake pedal must show: - Brake NOT pressed = OFF - Brake pressed = ON

4. TCU (automatic gearbox ECU) still interfering

If the automatic TCU is still connected or partially wired, it can block cruise logic.

Fix

• Fully disconnect/remove TCU
• Clear all related fault codes

5. Cruise stalk wiring (usually already OK)

Since cruise worked before the swap, this is least likely, but still verify:

• ON / SET / RES signals appear in measuring blocks

Quick diagnostic checklist (in order)

1. Recode engine ECU to manual
2. Verify clutch switch installed and working
3. Confirm 4-pin brake switch
4. Remove/disconnect automatic TCU
5. Check cruise stalk signals in VCDS

Most common single fix

ECU still coded as automatic + no clutch switch wired

If you want, provide:

• ECU part number
• Current ECU coding
• Whether clutch switches are installed (and how many)

I can give exact pin numbers and correct coding value.