Mercedes W204 C-Class ISM Repair — No Drive Fault | The Vehicle Check
The Mercedes W204 C-Class is one of the most common vehicles we repair for ISM (Intelligent Servo Module) faults. The W204 C-Class fitted with the 7G-Tronic gearbox uses an ISM module mounted directly on the gearbox body. When the ISM fails the gearbox has no drive in any position — the selector lever moves but the gearbox does not respond. Fault codes P0705 and P0706 are typically stored. The Vehicle Check repairs and clones Mercedes W204 ISM modules at component level.
W204 ISM Fault — Symptoms and Causes
The W204 ISM is exposed to gearbox heat and vibration throughout its service life. Internal solder joint fatigue, connector pin corrosion and power stage transistor failure are the primary failure modes. The fault typically presents suddenly — the vehicle is driven normally and then parked, and on the next start there is no drive in any gear position.
P0705 (transmission range sensor circuit malfunction) and P0706 (circuit performance) are the primary fault codes. U0101 (lost communication with TCM) may also be stored if the ISM has lost communication with the gearbox control module.
ISM Repair and Cloning for W204
We carry W204-specific ISM test data and repair procedures. Our bench test replicates the W204 gearbox environment and identifies the exact failed component within the ISM. We carry out component-level repair — resoldering failed joints, replacing driver transistors or connector assemblies — and test under load before return.
Where the ISM is beyond economical repair, we clone the original module data to a tested donor W204 ISM. The cloned unit fits and functions without any dealer programming.
Post Your W204 ISM to Us
Post your W204 ISM to The Vehicle Check, Enfield EN3 7PH. We return it repaired or cloned in 2 to 3 working days. Call 0203 489 2610 before sending.
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The Vehicle Check | Unit 8 Solway Business Centre | Tysoe Street | Enfield | EN3 7PH
📞 0203 489 2610 | 📧 info@thevehiclecheck.co.uk
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