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GM recalling certain eAssist models; up to 42,904 vehicles potentially affected by GCM issue
6 May 2013
General Motors (GM) is recalling certain model year 2012 and 2013 Buick LaCrosse and Regal, and model year 2013 Chevrolet Malibu Eco vehicles equipped with the eAssist light electrification system. (Earlier post.) Some of these vehicles have a condition in which the Generator Control Module (GCM) may not function properly. This could cause a gradual loss of battery charge and the illumination of the malfunction indicator light, GM said in its notice to the National Highway Traffic Safety Administration (NHTSA).
If these warnings are ignored, eventually the engine may stall and/or the vehicle may not start. In addition, there may be a burning or melting odor, smoke, and possibly a fire in the trunk. Potentially up to 42,904 MY 2012 and MY2013 vehicles may be affected.
Starting with the arrival of 2013 models, eAssist is standard on the Regal with the discontinuation of the 2.4L base model. For the 2012 model year, eAssist became standard for the larger Buick LaCrosse luxury sedan. The system is also applied in the Malibu Eco. (Earlier post.)
The latest version of the eAssist system, as applied in the new Malibu, consists of:
A 32-cell, 115V, 0.5-kW Li-ion battery pack (15 kW peak power) using cylindrical power-optimized cells from Hitachi. The power electronics and the pack are packaged in the “eAssist power pack” which includes the batteries (2 parallel 16-cell modules) and the power electronics, both of which are air-cooled.
An electric motor-generator that provides 15 kW of maximum generating power @ 1570-3180 rpm; 110 lb-ft (150 N·m) maximum electric motor torque (cranking); 79 lb-ft (107 N·m) maximum electric motor torque @ 1,000 rpm (electric assist); and 15 hp (11.2 kW) @ 1,000-2,200 rpm maximum electric motor power (electric assist). The motor generator is liquid-cooled.
The eAssist system is matched to a 2.4-liter gasoline engine. The system provides an electrical boost to aid the engine at low speeds and on inclines where fuel efficiency can suffer most.
Background. In May/June 2012, GM Product Engineering identified an increase in warranty cases regarding circuit board shorting in the GCM. GM engineers worked with the supplier to understand the root cause of the issue. A conditioning screening process was added to the manufacturing process at the supplier on a sample basis.
A technical assessment concluded there could exist an interlayer shorting between the conductive layers of a circuit board within the GCM. It further found that in the rare event that a short occurred in the metal-encased GCM, the short would not cause a fire outside the GCM and it would only cause odor, smoke, and/or soot.
The subsequent timeline on the issue was:
10 August 2012. GM Product Investigations was notified of an increase in warranty cases regarding this issue and an investigation was initiated
5 October 2012. GM decided to conduct a Service Update of unsold vehicles to screen them to determine if the GCM needed replacement.
24 October 2012. GM was informed of a vehicle that experienced a fire in the trunk while undergoing the service update screening procedure at a dealership. The product investigation was re-opened.
15 November 2012. GM expanded the service update population. A stop build I ship order was implemented and all vehicles at the assembly plant were screened prior to shipping.
25 March 2013. GM was informed about a fire in a vehicle that previously had the service update performed. The investigation of known field cases was expanded and all potential TREAD records were reviewed.
1 April 2013. NHTSA contacted GM regarding TREAD “Flammability” reports involving the subject vehicles.
25 April 2013. GM and NHTSA had a conference call to discuss the status of this issue.
29 April 2013. GM Executive Field Action Decision Committee decided to conduct a safety recall.
Dealers will perform the screening process and if necessary, replace the GCM. GM will provide the dealer bulletin and owner letter mailing dates when available. All involved vehicles are covered under the new vehicle warranty.
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