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Troubleshooting Ideas: Mercedes-Benz Cruise Control System
1981-Present (14-pin Amplifier, Motor Actuator)

Please note that these ideas and procedures are for someone who has the time, inclination and technical ability to understand and follow them. There are other alternatives. We can generally tell you, over the phone or by email, what is wrong with your system if you let us know what the symptoms are. Or, naturally, you can have your favorite local qualified mechanic perform the work. Please do not hesitate to email or call us if you have questions or concerns.

We all know the simplest thing to do is to simply plug in a new or remanufactured Amplifier without checking anything else. Please don't do that. There is the possibility of external cause for an Amplifier to fail. Following our simple test procedures should ensure that 1) you will spend minimal time troubleshooting the system and 2) you will probably not blow up a new or remanufactured amplifier because of excessive current draw from either a short in the system or a faulty Actuator.

If the vehicle already has one of our remanufactured Amplifiers there is no reason that our Amplifier should not last 30 years or more if it are not damaged by excessive current draw at the output section. We have well less than a half of one percent failure rate. It is rare that we have Amps returned to us at all but generally when one arrives it is either fine - something else is wrong with the system, or it has been blown by a faulty actuator.

Please note in the warranty that due care must be taken to keep the warranty valid. We take care that our remanufactured products are perfect when they leave here; the shop technician or vehicle owner must exercise the same diligence.

Before any amplifier is installed or even the Mercedes-Benz Cruise Control Test Fixture is employed, the technician must at least test the current draw of the actuator. Please see "Amplifier Pre-installation 'Actuator and Wiring Check' (Mercedes-Benz)" for this procedure. Actuator motor armatures can fail with shorted commutators thus drawing a couple amps from the Amplifier. This failure mode will fry an either amplifier or the Mercedes Test Fixture (we repair those occasionally also!)

Here are some non-Amplifier-related troubleshooting possibilities:

- 1) female Amplifier connector pins - it is wise to slightly crimp the female pins with an appropriate tool and check for corrosion.

- 2) brake light bulbs - the bulbs must not be burned out; the system gets a critical ground through the filament.

- 3) column switch - please see: "Cruise Control Switch and Speed Sensor Test."

- 4) speed transducer - same as 3)

- 5) Actuator - please see: "Amplifier Pre-installation 'Actuator and Wiring Check'"

- 6) Actuator connector - again, check for good electrical contact and corrosion

Just like the Amplifiers, Actuators can be intermittent or fail suddenly.

We have such high confidence in our service that we offer Lifetime Warranties on Cruise Control Amplifiers and Actuators! Please do not hesitate to call us if you have questions of any nature or need further assistance with troubleshooting the system.

Back to Cruise System Test - Table of Contents

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General Development Laboratories
3041 Sandalwood Avenue
Morro Bay, CA 93442
805 772-5127