U0193 Lost Communication with Digital Audio Control Module A

OBD-II DTC Datasheet

Lost Communication With Digital Audio Control Module A

What does this mean?

This is a generic communications system diagnostic trouble code that applies to most makes and models of OBD-II vehicles.

This code means the Digital Audio Control Module A (DACM-A) and other control modules on the vehicle are not communicating with each other. The circuitry most commonly used for communication is known as Controller Area Bus communication, or simply the CAN bus.

Without this CAN bus, control modules cannot communicate and your scan tool may not receive information from the vehicle, depending on which circuit is involved.

The digital audio control module a is usually located behind the dashboard, usually in the center of the vehicle. It accepts input data from various sensors, some of which are directly connected to it, and most are transmitted over a bus communication system. These inputs allow the module to control the information displayed and played back through the DACM-A.

Troubleshooting steps may vary depending on the manufacturer, the type of communication system, the number of wires, and the colors of the wires in the communication system.

Code severity and symptoms

The severity in this case is never serious, as this is a device for the convenience of customers. Lack of operation of the DACM-A does not in any way affect the operation of the vehicle.

Symptoms of a U0193 code may include:

DACM-A gives no information / sound / possibly blank screen
DACM-A does not turn on / does not work

reasons

Usually the reason for installing this code is:

Open on CAN bus + or - circuit
Short to ground or ground in any CAN bus circuit
No power or ground to DACM-A
Rarely - the control module is faulty

Diagnostic and repair procedures

A good starting point is always to check the Technical Service Bulletins (TSB) for your particular vehicle. Your problem may be a known issue with a known manufacturer-released fix and could save you time and money while troubleshooting.

First, look for other DTCs. If any of these are bus communication or battery / ignition related, diagnose them first. Misdiagnosis is known to occur if you diagnose the U0193 code before any of the major codes are thoroughly diagnosed and rejected.

If your scan tool can access trouble codes and the only code you are getting from other modules is U0193, try accessing the Digital Audio Control Module A (DACM-A). If you can access codes from DACM-A then code U0193 is either intermittent or memory code. If the DACM-A cannot be accessed, then code U0193 set by other modules is active and the problem already exists.

The most common failure is a circuit failure that results in a loss of power or ground to the digital audio control module a.

Check all fuses supplying the DACM-A on this vehicle. Check all the grounds for DACM-A. Locate ground anchorage points on the vehicle and make sure these connections are clean and secure. If necessary, remove them, take a small wire bristle brush and baking soda / water solution and clean each one, both the connector and the place where it connects.

If any repairs have been made, clear the DTCs from memory and see if U0193 returns or you can contact the DACM-A. If no code returns or connectivity is restored, the problem is most likely a fuse / connection issue.

If the code returns, look for the CAN bus connections on your car, most importantly the DACM-A connector, which is usually located behind the dashboard, usually in the center of the car. Disconnect the negative battery cable before disconnecting the connector on the DACM-A. Once detected, visually inspect the connectors and wiring. Look for scratches, scuffs, exposed wires, burn marks, or molten plastic.

Disconnect the connectors and carefully inspect the terminals (metal parts) inside the connectors. See if they look burnt or have a green tint indicating corrosion. If you need to clean the terminals, use an electrical contact cleaner and a plastic bristle brush. Allow to dry and apply electrical grease where the terminals touch.

Before reconnecting the connectors to the DACM-A, perform these few voltage checks. You will need access to a digital volt-ohmmeter (DVOM). Make sure the DACM-A is powered and grounded. Access the wiring diagram and determine where the main power and ground supplies go into the DACM-A. Connect the battery before proceeding with the DACM-A still disconnected. Connect the red wire of your voltmeter to each B + (battery voltage) power source going into the DACM-A connector, and the black wire of your voltmeter to a good ground (if unsure, the negative pole of the battery always works). You should see the battery voltage reading. Make sure you have a good reason. Connect the red lead from the voltmeter to battery positive (B +) and the black lead to each ground. Once again, you should see the battery voltage every time you plug it in. If not, troubleshoot the power or ground circuit.

Then check the two communication circuits. Locate CAN B+ (or MSCAN + circuit) and CAN B- (or MSCAN - circuit). With the black wire of the voltmeter connected to a good ground, connect the red wire to CAN B+. With the key on and the engine off, you should see a voltage of about 0.5 volts with little fluctuation. Then connect the red lead of a voltmeter to the CAN B circuit. You should see about 4.4 volts with slight fluctuations.

If all tests pass and communication is still not possible, or you were unable to reset DTC U0193, the only thing to do is to seek help from a trained automotive diagnostician as this will point to a faulty DACM-A. . Most of these DACM-A's must be programmed or calibrated in order to properly install the vehicle.

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