2002 Mercedes-Benz ML320
NHTSA Defect Investigations
The Office of Defects Investigations (ODI) is an office within the NHTSA which investigates serious safety problems in the design, construction or performance of vehicles. The NHTSA is authorized to order manufacturers to recall and repair vehicles, if the ODI finds a safety issue. NHTSA investigations for the 2002 Mercedes-Benz ML320, both ongoing and closed, are listed below:
INVESTIGATION: BRAKE LINE CHAFE
NHTSA Engineering Analysis #EA08009
Component(s): Fuel System, Gasoline:Delivery:Hoses, Lines/Piping, And Fittings
Service Brakes, Hydraulic:Foundation Components:Hoses, Lines/Piping, And Fittings
Summary: Analysis of complaints to ODI and Mercedes and warranty claim data submitted by Mercedes indicates that the alleged defect has occurred at a low rate (36.5 complaints per 100,000 vehicles and 0.29 percent warranty claim rate), with no discernable defect trend indicating that the rate of chafing related brake line failures is increasing.there have been no new complaints since January 2009.when the analysis is limited to incidents of brake line leakage that resulted in allegations of reduced brake effectiveness, the rate drops even further (22.3 complaints per 100,000 vehicles and 0.04 percent warranty claim rate). Mercedes provided data showing that in the rare instances when chafing did progress to brake line leakage the driver would be immediately alerted to a problem by illumination of the bright yellow "esp/bas" warning lamp and changes in brake pedal feel.continued operation with a leaking brake line would result in illumination of the bright red "brake" warning lamp and an audible chime due to low master cylinder reservoir level. Continued operation with the brake warning lamp illuminated would ultimately drain the reservoir for the affected circuit, resulting in loss of the circuit and an approximately 80% increase in stopping distances. Surveys conducted by ODI and VRTC indicate that routing anomalies may be more common than the complaint and warranty data suggest for the subject line bundle, with line contact or other routing anomaly noted in 13 of 51 vehicles surveyed by ODI and VRTC (25.5%).while evidence of contact between the fuel line and subject brake in a particular vehicle is not necessarily predictive of eventual line failure/leakage, significant chafing wear was noted in two survey vehicles (3.9%).to address concerns with line routing and ensure that lines with evident chafing do not progress to a leak condition, Mercedes will conduct an owner notification program instructing owners to bring the vehicles to a dealer for a free inspection and repair.lines that do not have a spacer (rubber grommet or omega-clip) between the subject fuel and brake lines will have an omega-clip spacer installed to ensure adequate clearance between the lines.brake lines with chafe marks will be replaced. Accordingly, this investigation has been closed. The closing of this investigation does not constitute a finding by NHTSA that a safety-related defect does not exist. The Agency will continue to monitor complaints and other information relating to the alleged defect in the subject vehicles and take further action in the future if warranted. For additional information regarding this engineering analysis refer to the EA08-009 closing report.
INVESTIGATION: Brake lamp switch failure.
NHTSA Preliminary Evaluation #PE10050
Component(s): Service Brakes, Hydraulic
Service Brakes, Hydraulic:Switches:Brake Light
Vehicle Speed Control
Vehicle Speed Control:Cruise Control
Summary: ODI opened the investigation based on reports that the subject vehicle brake lamp switch (switch) failure caused 1) inoperative brake lamps (stay on or fail to illuminate), and/or 2) shift interlock failure (shifter locked in park), and/or 3) the cruise control to fail to cancel with brake application.Consumers also reported the illumination of a warning lamp on the instrument panel.The switch contains three sets of electrical contacts and a (normally extended) spring loaded plunger that actuates the contacts as it moves.As installed in the vehicle, the plunger contacts the brake pedal arm and is pushed into the switch; as the driver applies the pedal the plunger extends.One set of contacts (BLS) operates the stop lamps, a second set (EWM) controls the shift interlock system, and a third set (BS) is used by an on-board diagnostic (OBD) system to monitor switch operation.The cruise control monitors the BLS signal to determine when the brake is applied, the primary way the system is disabled when set.The relative timing of contact actuation in response to plunger movement allows the OBD system to detect a switch fault.When a fault is detected a malfunction indication lamp (MIL) is illuminated (driver alert), a diagnostic trouble code (DTC) is stored (for the service technician), and cruise control operation is inhibited (as a failsafe).In its response to ODI's January 2011 information request letter, MB explained its assessment of switch failures which was based primarily on evaluation of field return failures.MB identified both 1) electrical contact and 2) mechanical switch failure mechanisms.According to MB's analysis, electrical contact failure is the predominate failure type and the failure consequence depends on which contact fails.For instance MB claims that BLS contact failures are momentary in nature and do not affect brake light operation but are nonetheless detected by the OBD system, resulting in a DTC and subsequent replacement.Electrical contact failures of the BS and EWM contacts result in a DTC also, and EWM contact failures result in the shifter being stuck in the park (which can be overridden by the consumer).Accordingly MB maintains that electrical contact failures of the switch have no safety consequence since the brake lamps remain operational and the cruise control is always disabled.MB determined that mechanical failures of the switch, which are rare in their assessment, can result from internal wear and/or increased switch operating temperatures.High temperatures occur due to overheating of the BLS contacts and can cause the internal plastic components to melt.In one scenario overheated BLS contacts may melt to the extended plunger and are damaged when the brake pedal is released resulting in the brake lights staying on.In another scenario the increased temperatures and/or internal wear can cause the plunger to stick in the fully depressed position.In this case the cruise may not cancel when the brake is applied and the driver may have to use high brake pedal forces or other means (shifting to neutral or using the cruise master switch) to disengage the cruise.Additionally the vacuum assist can be depleted if the driver pumps the brakes resulting in reduced braking effectiveness and even higher pedal forces.In its March 31, 2011 defect notification, MB stated that to remediate the potential need for excessive brake force it would conduct a safety recall (11V-208) to replace the switch with a more robustly designed component.The recall includes 136,751 model year 2000 - 2002 M-Class and model year 2000 - 2004 M-Class AMG vehicles.Owner notification letters will be mailed to consumers in September 2011.This action taken by MB is sufficient to resolve the issues raised by this investigation.
INVESTIGATION: POWER STEERING HOSE LEAK
NHTSA Defect Investigation #RQ08002
Component(s): Steering:Hydraulic Power Assist System
Steering:Hydraulic Power Assist:Hose, Piping, And Connections
Steering:Hydraulic Power Assist:Power Steering Fluid
Summary: Mercedes-Benz usa (mbusa) will notify certain model year (MY) 1998 through 2003 M-class owners of the need to bring their vehicles into dealers to address the issue previously campaigned under mbusa recall 2003-040005 (NHTSA recall 03V-121).the mbusa campaign, which ODI is designating recall 08V-465, will replace the power steering cooler hose and clamp in all vehicles that received the original recall remedy for 03V-121 and which haven't received a subsequent repair to install a revised hose and clamp.approximately one-third of the vehicles that received the original repair procedure and parts returned for subsequent service for leakage from the hose fitting and, in approximately 10 percent of these vehicles, complete separation of the hose from the cooler.a revised service procedure for 03V-121, which involved replacing the old hose and clamp with modified parts, had significantly lower rates of return repairs.mbusa will apply the revised service procedure from 03V-121 to the vehicles covered under 08V-465.accordingly this recall query is closed.