Mercedes ISM DSM Gear Selector Cloning and Repair
The Mercedes ISM (Intelligent Servo Module) and DSM (Direct Select Module) are the gear selector control units fitted to Mercedes 7G-Tronic and 9G-Tronic automatic gearboxes. When these modules fail the result is no drive in any gear, a gear selector that does not respond, or fault codes P0705, P0706 and U0100 stored in the gearbox control unit. The Vehicle Check specialises in ISM and DSM cloning, repair and bench testing. We cover the full Mercedes range — C-Class, E-Class, S-Class, GLC, GLE, Sprinter and Vito — via our nationwide mail-in service.
ISM and DSM Faults — What Goes Wrong
The ISM is mounted on the 7G-Tronic gearbox body and controls the electrohydraulic gear selection mechanism. The DSM (fitted to later models with the column-mounted or centre console Direct Select lever) connects the driver's gear input to the TCM. Both modules are susceptible to internal PCB faults, connector corrosion and power supply failure — often triggered by water ingress or a voltage event.
Common symptoms include the gear selector not registering any input, the vehicle stuck in park with no response, P0705 (transmission range sensor circuit malfunction) or P0706 (transmission range sensor circuit performance) stored, and in some cases a complete loss of drive with the gearbox locked in neutral.
Cloning vs Repair
Where the original ISM or DSM is physically damaged beyond repair — due to water damage, heat damage or a severe voltage spike — cloning is the preferred solution. We read the module data from your original unit and transfer it to a tested donor module, preserving all gearbox adaptation values and vehicle configuration data. The cloned unit fits directly without dealer reprogramming.
Where the unit has an internal fault but the board is intact, we carry out component-level repair — identifying and replacing the failed transistor, relay or power stage component. All repaired and cloned units are bench tested before return.
Models and Applications Covered
We cover ISM and DSM units across: C-Class W204, W205, E-Class W212, W213, S-Class W221, W222, GLC X253, GLE W166, W167, CLA C117, CLS W218, Sprinter 906 and 907, Vito W639 and W447.
Post your ISM or DSM to our Enfield workshop. We return it repaired or cloned within 2 to 3 working days. Call 0203 489 2610 to discuss the fault before sending.
Send Your Unit Today
The Vehicle Check | Unit 8 Solway Business Centre | Tysoe Street | Enfield | EN3 7PH
📞 0203 489 2610 | 📧 info@thevehiclecheck.co.uk
Nationwide mail-in postal service. All work covered by our repair warranty.