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Upfit FAQ for Chevrolet Police Vehicles, Part 1
This issue of Police Fleet Manager begins a three-part series of answers to frequently asked questions (FAQ) concerning features, function and upfitting of the 2008 Chevrolet Impala (9C1 or 9C3) and Tahoe 2WD (PPV) police package vehicles and Tahoe 4WD (5W4) special service vehicle. Before beginning an upfit, detailed information can be found on two Internet Web sites.
First, try www.gmfleet.com, linking to “Government” to find the GM Fleet and commercial law enforcement vehicles. Second, go to www.kerrindustries.ca for dealer direct order of useful non-OEM police vehicle wiring and equipment features. The information at these Web sites is also available on free CDs by calling GM Fleet and Commercial Sales at (800) 353-3867.
Each Impala and Tahoe emergency vehicle package is assembled and delivered to a Chevrolet dealer with an owner’s manual supplement. If the booklet is not found in the vehicle, we recommend that upfitters attempt to obtain a copy of the supplement before starting an upfit to take advantage of the detailed information provided.
Question 1: May I remove the metal box structure (crush box) mounted between the seats of the Impala police package with bucket seats to facilitate installation of communication and emergency lighting controls console?
Answer: No. The 2006-2008 Impala structure is designed to provide improved resistance to side impact. The doors are interlocked to the body structure when closed, and the front seats have lateral load beams. The crush box is intended to transmit side impact loads from seat to seat as part of the total vehicle system, including roof-rail airbags, to meet the requirements of Motor Vehicle Safety Standard 214, “Side Impact Protection.” Removal of the crush box to facilitate aftermarket equipment may reduce the effectiveness of the Impala to withstand side impact and is not recommended. Mounting of small screws, ¼-inch diameter maximum, in the crush box to secure aftermarket equipment is permissible.
Question 2: How does the park-enable feature work? When I test for power, there is no voltage on the Impala yellow / black wire. On the Tahoe yellow / black wire, I get less than the voltage needed to operate a relay.
Answer: The Impala and Tahoe park-enable features operate in an opposite manner because of different connection to the body control module (BCM) in each vehicle. The BCM circuit in each case is designed to operate one customer furnished relay by applying 12 volts to the relay. In both vehicles, the relay must be connected (high side of coil to the yellow / black signal wire, low side to ground) and the engine must be running.
The Impala BCM circuit is “hot out of park” (12 volts present) and no voltage in park. The Tahoe BCM park-enable circuit is “hot in park” (12 volts present) and no voltage out of park. A relay may be required to provide the desired signal (normally open or normally closed) to control the aftermarket equipment.
Question 3: How can I separate the headlamp flashing from the rear lamp flashing?
Answer: The Impala and Tahoe are designed with an in-line connector in the forward lamp harness for connection of a flasher module, Option Code 6J7. The Impala flasher module is mounted at the inboard end of the right headlamp, and in the Tahoe, the module is mounted forward of the right-hand wheelhouse inner fender. When the flasher is ordered and installed, it is connected to the in-line connector and is activated by applying 12 volts to the blunt-cut dark green / red 18 awg wire located under the instrument panel. This wire is usually connected by the upfitter to an exterior emergency lamp controller.
When activated, the module flashes the high beams alternately and applies a ground to the BCM via pin F of the in-line connector. The ground signal causes the BCM to flash the stop lamps and backup lamps alternately. To separate the front and rear flashing functions, remove the blue / yellow wire from cavity F of the in-line connector. Connect a new wire of the same gage and color to the wire removed from cavity F and route it to an emergency lighting controller inside the passenger compartment. Connect to the controller so that it will provide a ground signal (Not 12 volts or the BCM may be damaged) to the desired position of the controller switching.
Question 4: How do I stop my Tahoe headlights from flashing and the horn from chirping when I use the remote key fob?
Answer: The Tahoe police and special service (5W4) packages can be taken to your Chevrolet dealer and reprogrammed to disable the approach lighting, visible or audible feedback and key fob panic button. Automatic door locking and ingress-egress lighting can also be disabled. The vehicle must be a PPV or 5W4 and owned by a qualified governmental agency.
The dealership will require a letter on official agency letterhead providing specific Vehicle Identification Numbers (VIN) and requesting the feature(s) to be disabled. The agency must agree to enable the requested features when the vehicle is removed from service.
Published in Police Fleet Manager, Mar/Apr 2008
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