W202 cruise control cuts out? Check control unit A0145454032
Short answer: If the cruise control in the Mercedes C-Class W202 (C 220, C 280) cuts out again after 20 to 40 seconds, the speed hunts, or it is not stored at all, the aged digital VDO control unit is often the cause. For these models, the control unit A 014 545 40 32 with coding plug A 014 545 88 32 is specified. The replacement is a tested genuine part with renewed capacitors for 289,00 €.
Cruise control set, foot off the gas – and a moment later the car loses speed again. Or the control “hunts”: the W202 speeds up, then slows down, without you doing anything. Many drivers of a C-Class from the 1993 to 1996 model years are looking for exactly this fault symptom. After around 30 years, the digital cruise control unit is one of the components where we see the most failures. Before you replace it, though, you should rule out a few cheaper causes – and above all check whether the control unit and coding plug match your vehicle.
Symptoms
The control unit evaluates the speedometer signal pulses and uses the electric actuator on the throttle linkage to regulate the set speed. The attached coding plug tunes the control behavior to the engine and vehicle. This gives rise to typical patterns:
| Symptom | Likely cause |
|---|---|
| Cruise control switches off again after 20 to 40 seconds | Aged capacitors or cold solder joints in the control unit |
| Speed hunts (surging), control is jerky | Control unit regulates incorrectly or wrong coding plug attached |
| Speed is not stored, fuse and connector OK | Control unit failure |
| Cruise control cuts out, brake light does not light up or stays on permanently | Cause at the brake light – the control unit deliberately disengages when braking |
| Same fault symptom, but on the W124 with control unit A 005 545 05 32 | Not to be confused with: different model series, different unit – see W124 cruise control cutting out? Check control unit A0055450532 |
Causes
The control unit contains electrolytic capacitors that dry out over the years and lose capacitance. The internal power supply becomes unstable, and the unit “forgets” the stored speed or regulates erratically. On top of that, solder joints crack from temperature changes and vibration and cause sporadic failures – the fault then appears on and off.
A second, often overlooked cause is the coding plug. It defines the vehicle-specific control characteristic. If a control unit was installed with the coding plug of a different vehicle during an earlier repair, the control can hunt even though the unit itself works. The control unit is located in the interior, depending on the version in the footwell under the carpet or under the dashboard – moisture in the footwell additionally attacks the connector and circuit board.
Testing it yourself
Start with the cheapest – the first steps cost nothing.
- Check the brake light. The cruise control cuts out when braking. Have someone check whether the brake lights come on and go off cleanly. A faulty brake light signal interrupts the control.
- Watch the speedometer. Does the speedometer needle read steadily and plausibly? Without a clean speed signal the control unit cannot regulate. If the needle twitches, the problem lies upstream of the cruise control – hints on this in the guide Mercedes speedometer stuck: Repair odometer & speedometer needle.
- Check fuse and connector. Check the relevant fuse according to the wiring diagram and the connector on the control unit for corrosion or moisture.
- Observe the actuator. If the throttle linkage moves when the cruise control is set, an actuating command is arriving. If the control then drops out after a short time, that points to the control unit.
- Read off the part number and coding plug. Note the number of the control unit and that of the attached coding plug. According to Mercedes, the coding plug A 014 545 88 32 belongs with the W202 C 220 and C 280. Swapping in an identical unit is the most reliable test.
Solution
If the suspicion is confirmed, the control unit is replaced: disconnect the battery, expose the control unit, pull the connector, and fit the replacement unit in the same position. We supply a used genuine control unit A 014 545 40 32 with attached coding plug A 014 545 88 32 (VDO 412.212/001/004 · 519.201/1/47), tested and with renewed capacitors – not aftermarket. No core charge is applied.
Cruise control unit A0145454032 – digital, with coding plug
Coding plug A 014 545 88 32 · VDO 412.212/001/004 · Capacitors renewed
Listed for W202 C 220 (202.022) and C 280 (202.028), 1993–1996
289,00 €
View control unitImportant for vehicles of other model series: The control unit (superseding number A 023 545 21 32) runs there with a different, vehicle-specific coding plug – in that case, reuse the coding plug from your vehicle. Older analog units without a coding plug, such as A 003 545 09 32, are not directly interchangeable. You can find more tested control units in the category Mercedes relays & control units.
Compatible vehicles
The overview reflects only what's documented for this part.
| Model series | Models | Note |
|---|---|---|
| C-Class W202 (1993–1996) | C 220 (202.022), C 280 (202.028) | Coding plug A 014 545 88 32 according to Mercedes for these models |
| other model series | only with their own vehicle-specific coding plug | Compare the part number before buying |
| does not fit | Vehicles with ASR or electronic accelerator pedal (E-Gas) | likewise cruise controls with a pneumatic actuator |
What counts is always the number on your removed control unit and coding plug. With your VIN (chassis number) and model year, we check the fit free of charge.
FAQ
Why does the cruise control in the W202 cut out again after a short time?
Typical for an aged control unit: the capacitors lose capacitance or solder joints crack, and the unit then loses the stored speed after 20 to 40 seconds. Check the brake light and speedometer signal beforehand, since the control unit also evaluates both.
Which cruise control unit belongs in the W202 C 220 and C 280?
For the W202 C 220 (202.022) and C 280 (202.028) from the 1993 to 1996 model years, the digital VDO control unit A 014 545 40 32 with the coding plug A 014 545 88 32 is the listed combination.
What is the coding plug A 014 545 88 32 for?
The attached coding plug tunes the control behavior of the control unit to the engine and vehicle. A wrong coding plug can lead to a hunting speed, so it should match your vehicle.
Does the control unit also fit vehicles with ASR?
No. This control unit is not suitable for vehicles with ASR or electronic throttle (E-Gas), nor for cruise controls with a pneumatic actuator.
How much does a tested cruise control unit for the W202 cost?
The control unit A0145454032 with coding plug costs 289,00 Euro per piece. It is a used genuine part, tested and with renewed capacitors; currently 2 pieces are in stock.
KFZTeile-Thot is a specialist company for tested and refurbished Mercedes parts with its own test benches. Control units and relays are tested here before shipping – over 1,000 positive eBay reviews reflect that. Not sure whether the control unit and coding plug fit your vehicle? Call us at +49 179 8991069 (Mon–Fri 8 am–6 pm) or write via our contact form – fastest with the VIN and the number of your control unit.