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Charger Tech Training: Body Electrical Course for Upfitters

Written by PFM Staff

Ed. note: Charger Technician Training, in a wide variety of two-day training blocks, is available at dozens of Chrysler training locations across the U.S. There is no prerequisite for the training, and it is open to all fleet personnel, from the fleet manager to the maintenance and repair technician.

This is the same factory training given to dealership technicians. The same police-specific training will also be available in-house at police and sheriff’s departments running larger fleets of Chargers.

For more information on Charger Technician Training, contact Fleet Service Manager George Bomanski, Chrysler Group, (407) 257-1532, gmb5@chrysler.com. This training is scheduled about six months in advance. Because the training is definitely hands on, the class size is limited to 12 techs.

The Body Electrical Course is especially important for upfitters. Heads-up: The electrical architecture for the 2006-2007 Chargers and the 2008-2009 Chargers is very different.

The factory provides up to 120 amps for the police upfit. The police Charger has three 20-amp connections wired through the ignition switch and three 20-amp connections wired directly to the battery. If you need more than 20 amps for any one circuit, you cannot use any of the LX body electrical circuits.

The number one rule for upfitters from the Body Electrical Course is: Do NOT tap into the CAN bus anywhere, for any reason! We’ll explain why.

Upfitter’s Guide

The Upfitter’s Guide is a 56-page manual, and it is available free on the Chrysler Web site. In the manual are all of the amp loads (current draws) from the retail Charger.

The best reason to strictly follow the Upfitter’s Guide is to save you when you take the vehicle in to a dealer with a troubleshooting problem. What happens when any upfitted police vehicle with an electrical concern (on the car, not the police gear) rolls into the service bay of any dealership? What is immediately suspected as the fault? The upfitted police gear, of course. The dealership will assume all the police gear is incorrectly installed.

Now, if the factory Upfitter’s Guide is strictly followed, the dealer will be able to diagnose the vehicle properly, knowing that the vehicle is electrically separated from, or properly incorporated into, the police gear.

The Upfitter’s Guide is full of both cautions and warnings. Here is the difference between these two. If you violate a caution, you will bleed, wear a scar and be the butt of shop jokes for a while. If you violate a warning, that is a whole other thing. “Warning” signifies extreme danger, like the fact that the airbag capacitor holds its full charge of electricity for two minutes after the battery is disconnected.

During the Upfitter’s Course, you review the Upfitter’s Guide page by page and, in some cases, line by line. Time is spent on the details of what is located where, and where or where not to drill. However, time is also spent on the bigger issue of amp load (current draw).

Pop quiz: How do you change the wig-wag rate of the headlights and the flash rates of the tail lights? Answer: These flash rates cannot be changed.

Police-Specific Power Distribution

The Upfitter’s Course includes a review of every pin and cavity on the police-specific connectors and modules and on the two power distribution centers. It also includes a detailed review of Charger wiring schematics. The “A” fused connections to the battery (B+) are hot all the time, while the “F” connections through the ignition are hot only when the ignition is on.

The Police Accessories Connector is a 12-cavity auxiliary power source connector with six 16-gauge provided circuits and room for six other (supplemental equipment) wiring circuits. A 12-way mating connector is available as an accessory. This is Mopar P/N 05191127AB. This Mopar part is actually a variety pack that contains three different connectors and terminals: one kit for the 12-way Police Accessories Connector, one kit for the 24-way Police/Taxi Interface Module and one kit for the three-way Police Radio Connector.

So, that 12-way connector has three 16-gauge B+ terminations, three 16-gauge key-on terminations, and six terminations that become the three twisted pairs behind the front fascia. These three pairs of coiled wires are bare, non-terminated on the end by the engine oil cooler. The ends located under the instrument panel center stack are terminated in the 12-way Police Accessories Connector.

First the 22 cavities of the front PDC, then the 47 cavities of the rear PDC and finally the 12 cavities of the police fuse/relay block. The police fuse/relay block is located at the right-hand side-kick panel.

The 12-cavity Police Accessories Connector is not to be confused with the 24-cavity Police/Taxi Interface Module (PTIM)! The PTIM is the key to the front and rear flashing lights signal, horn switch sense, police radio input signal, Park/Neutral switch sense, Vehicle Speed Signal, etc.

The Upfitter’s Course also demonstrated how to get to the 12-cavity connector and the 24-cavity connector. The center console must be de-trimmed, and the PTIM must be removed from its mounting bracket.

Police Alternato­r

The police Charger has an alternator with a best-case rating of 160 amps. Of course, the in-service police Charger never sees that 160-amp output. Alternator output varies a great deal by temperature, and the 160-amp rating is taken in a controlled environment test lab. With underhood temperatures of 200 F, the police Charger has an output of 90 amps at low idle (625 rpm), 120 amps at high (Park) idle (1200 rpm) and a maximum output of 140 amps at 2500 rpm.

The base vehicle with no police gear needs a great deal of current to run and power the various vehicle accessories. For example, the Charger needs 23 amps just to idle, 48 amps to run the radiator fans, 23 amps to run the air conditioning and 29 amps to light up the high beams.

This police Charger, idling on a hot day with the A/C and bright lights on, takes 123 amps. Under this condition with no police gear whatsoever, the Charger uses all the current the alternator produces. Any additional power comes from the battery, thus draining it.

All this is a heads-up that a limit exists to how many power-consuming communication and emergency devices can be added to police vehicles. The manufacturer of all aftermarket devices will be able to tell you how much current the devices draw and under what conditions.

One of the class exercises was to find the amp draw required by the Charger under the worst case conditions, with no police gear. From there, it is a simple (but critical) task to add up the amp draw from all the electronics and electrical gear added during the upfit.

Occupant Restraint

One of the blocks of instruction involved the steering and related occupant safety and restraint systems. The LX platform vehicles use the Bosch 8.7E Occupant Restraint Controller (ORC). This multi-point, multi-stage module has two 32-way connectors and is located on the tunnel under the instrument panel. The ORC deploys front airbags, front seat pretensioners, side (thorax) seat airbags and side (roof rail) curtain airbags.

Here’s a bit of airbag safety for upfitters and maintenance techs: The airbags remain active and armed for two minutes after the battery has been disconnected! A capacitor holds the full electrical charge to allow the airbag to properly inflate even if the battery connection is severed. Give those devices two full minutes to power down!

The LX has an Occupant Classification System that uses four strain gauges, located at each corner of the front seat frame where the frame attaches to the rise. Data from each strain gauge (sensor) is sent to the Occupant Classification Module (OCM), which in turn sends signals to the ORC.

The message to upfitters is clear: Don’t mess with the seat mounting bolts on the seat track rails! You can’t just unbolt the seat, slide some piece of upfit gear under it and bolt it back. And you certainly cannot simply use the seat mounting bolts as an attachment point for a partition, leg extension or center console.

The entire weight of the seat is supported by the strain gauge. The four seat weight sensor circuits involve a 5-volt supply, a signal wire and a sensor ground. Based on the change in voltage from the strain gauge, the OCM estimates the weight on the seat. It then classifies the seat as empty, rear-facing infant seat, child or weight greater than fifth percentile adult female. The force of the airbag, or whether the airbag is suppressed, is determined from the weight.

Any time the seat is removed, or any of the seat or track fasteners are loosened or tightened, the seat bolts must be precisely torqued, and torqued in a specific sequence. A service weight tool is needed to validate the system before clearing any DTC faults. Finally, a scan tool is needed to re-zero or re-initialize the OCM.

The steering column module assembly contains the Steering Column Module (SCM), multi-function switch and stalk, steering angle sensor and clock spring. The clock spring contains circuits for the multi-stage airbags. The SCM operates on both the CAN C and CAN B bus. The SCM has one power (B+) wire, one ground wire, two CAN C wires and two CAN B wires. Power comes from the rear PDC.

The upper side of the SCM has four docking connectors. The lower side has a 16-way connector that connects to the vehicle harness. The steering angle sensor connects to the SCM with a 10-way connector. The SCM contains seven LEDs and seven photocells. A flange on the clock spring interrupts the light beams, and this is used to determine the speed and direction of wheel rotation.

The steering wheel switches connect to a low speed bus called a Local Interface Network (LIN). Functions sent over this LIN bus include horn, volume up/down, compass-temperature, audio mode, menu scroll up/down and lighting level.

Pop quiz: Does the entire steering column assembly need to be replaced if just the front airbag deploys? Answer: Yes. This includes the complete column assembly with the lower steering column coupler, the stability control steering angle sensor and clock spring, the driver’s side airbag and the steering wheel.

Twin Saddle Tanks

The saddle design of the Charger fuel tank requires two fuel pumps and two sending units. An electric gear rotor motor with sending unit is located in the left sump, which is the primary side. A scavenger pump, sending unit, pressure regulator and outlet fittings are located in the right tank, which is the auxiliary side.

The output of the electric pump in the 12-gallon driver’s side is sent to the auxiliary side, where the pressure is regulated down and sent to the engine’s injectors. A port on the pump provides a pressure tap that routes a small amount of fuel to the scavenger pump, which provides a venturi effect.

During operation, the pump continuously tries to scavenge (or empty) the 7-gallon auxiliary side and fill the primary side. As a result, both tanks are emptied at exactly the same time. All connections between the main and scavenger pumps are enclosed within the tank assembly. The venturi effect causes a pressure drop and is the principle carburetors have worked off of for 100 years. The fuel pump scavenging (or balancing) from side to side works even if the gas cap is not in place.

When the tank is full and the fuel is level on both sides, the CCN averages the input from both sending units. When the fuel level becomes low enough that sloshing no longer equalizes the fuel level, the scavenger pump begins to transfer fuel from the auxiliary side to the primary side.

The tank is not made up of separate saddle tanks; instead, there is an upside-down U (i.e., one tank when full with a sump on either side). At less than half a tank, the sumps are not connected, except by hoses.

Pop quiz: What is the operating pressure of the police Charger electric fuel pump? Answer: While the live pressure to the fuel injectors is regulated down to 58 psi, the fuel pump pressure is180 psi.

Published in Police Fleet Manager, May/Jun 2010

Rating : 10.0


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