Most Mercedes Benzes made in 1993 to 1995 have problems with throttle bodies also known as electronic throttle actuator or ETA. Most ETA’s problems are due to shorting wiring inside ETA loom and some due to internal components failures. When ETA fails car goes into so called “ Limp Mode”. On this page you find common symptoms of faulty ETA and explanation of my repair service.
There are ASR and Non-ASR vehicles. ASR (acceleration slip regulation aka traction control) equipped vehicles enter into Limp mode with ASR and, in some cases, ABS warning lights illuminate on the dash. Symptoms: no acceleration when depressing gas pedal until halfway down, no power at acceleration, RPMs raise and lower chaotically, idle is higher than normal, ABS and ASR warning light are on (ASR equipped cars), cruise control either doesn’t work at all or doesn’t keep preset speed or disengages. Transmission shifts rough, stays in gear and shifts at higher RPMs unless you let go off the gas.
Cars that are not equipped with ASR option have slightly different symptoms-engine accelerates more or less normal, idle is higher than normal and can raise and lower by itself, cruise control doesn’t work, ABS light can illuminate on dash in some cases but in most cases “Check Engine” light is lit and codes come for ISC-idle speed control.
In both ASR and non-ASR cars transmission engages harsh due to higher than normal idle speed.
Throttle bodies made in 1993 for 600SL ONLY and all others made in 1994-1995 along with few 96 6 cylinders models have biodegradable wiring insulation that will fail and wires short. Some very few throttle bodies, about 1%, are not repairable due to wear and have to be replaced. Some ETAs, about 5%, have internal parts failures on top of shorting wires that can be repaired. In some cases shorting wires burn E-gas module in ASR cars and T/LLR module in Non-ASR cars. Those modules will need to be replaced after rewired ETA installed back into the car. I do not repair throttle control modules. I only take in SL600 E-gas modules for repair due to their very high price and very limited availability. It is suggested not to drive the car in Limp Mode as there are risks of burning E-gas module, damaging transmission and even engine internals due to harsh transmission engagement and higher than normal RPMs.
96-up V8 and V12 along with 97-up 6 cylinder engines ETAs are different from older units. They don’t have pigtails anymore and main harness plugs directly into ETA. These newer ETAs fail due to internal plastic gears or potentiometer failures and need to be replaced. I do not repair 97-up throttle actuators (96-up for V8 and V12 engines)
E-class and C-class vehicles used pigtail ETA until 97. These ETAs are known to have biodegradable insulation on wiring that crack and fall off. Those need to be rewired.
If you experience problems with your throttle body feel free to contact me and I will be able to repair your ETA. At Mercedes dealer new ETAs cost range from $1200 up to $5400 for V12 models each. And it doesn’t make sense to buy used ones as they use same biodegradable wiring insulation that can fail pretty fast. Even if ETA worked fine in the car it came from wiring fails as loom gets bent and twisted during removal. I have lots of customers who lost money buying used ETAs that failed either right away or after some sort time after. In the end they had their original ETAs mailed to me for repair.
Some small percentage of ETAs, about 5%, have internal parts failures. I have repaired motor brushes, electromagnetic clutch coils, replaced potentiometer metal sliders. These parts are examined during ETA disassembly and bench test prior to rewire and customer is informed on any issues with internals.
REPAIR PRICING as of 2018:
As of 2018 repair prices are below plus shipping and processing cost. There is 3% processing fee for PayPal and Credit Card payments.
93-95 6 cylinders ETA rewire - $375. Many 6 cylinders ETAs have clutch coil failure. Coils are inspected before rewire.
94-95 8 cylinders ETA rewire - $400
93 (600SL ONLY) 94-95 V12 throttle rewire - $450 each. IMPORTANT NOTE: some 94 and all 95 V12 units have internal motor design flaw. Motors brushes get stuck inside holders and if not repaired will melt holders. It is highly recommended to free brushes before they melt holders. When holders are melted complete ETA needs replacement as there are no replacement motors available. Brush repair is $250 per ETA. 93 600SL have different motors design, brushes do not fail as often.
Clutch coil or motor repair on ASR models - $150
Clutch coil repair on non-ASR units - $300. Grinding, welding, throttle plate alignment required to repair clutch coil on these models. It is labor intensive process.
One can check internal wiring insulation by making 2” incision along center of actuator loom, spreading outer cover apart and inspecting wiring. Below are pictures of bad wiring. Also, check production date before mailing unit over. Scroll down for throttle actuators general information video and removal instructions
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