Audio System - Troubleshooting
Bulletin: P93/86-003Section: Product
Date: 2/10/93
Model: Range Rover
Applicable to: USA/CND
Subject:
1993 AUDIO SYSTEM
The following information should be used to troubleshoot problems with the 1993 Range Rover audio system.
It includes three diagnostic procedures and complete system wiring diagrams. Use the index in this bulletin to match the complaint with the appropriate diagnostic procedure.
The 1993 system is technically less complex than the 1991 or 1992 premium audio systems and should require less diagnostic time to uncover faults. The information in this bulletin should be considered primary repair information for the system itself. For more detail on the vehicle portion of the audio harness, refer to the 1993 Electrical Troubleshooting Manual, Section E7.
System description:
The a/d/s/ music system in the 1993 Range Rover is made up of parts supplied by a/d/s/ along with parts supplied by Pioneer and Land Rover.
Because all functions of the audio system are interrelated, the symptoms of a problem may appear to be in a different part of the system than the offending component. For example, a symptom of no subwoofer output may be due to a defective subwoofer, a defective amplifier, a bad cable, or simply to a mis-adjusted tone control. it is the purpose of this guide to help you narrow down the choices to the one actually causing the problem and minimize the time necessary to weed out the offending component. The three troubleshooting procedures below, should help you diagnose the most common system problems.
Unfortunately, no one can anticipate all of the problems that may arise, so we have included an operational schematic and connector pin diagrams in the rear of this document to help trace unusual problems. Because the 1993 system has been greatly simplified when compared to previous year systems troubleshooting is greatly simplified. Except for those annoying intermittents, most problems should be able to be diagnosed in less than 15 minutes.
As before, if the cause of a specific problem is elusive, please call us at a/d/s/ at 1-800-522-5534 for assistance.
Troubleshooting common problems:
Because of the greater simplicity of the 1993 system compared to those in 1991 or 1992, most problems may be broken down to three areas.
1. Power supply related problems: either + voltage or ground.
^ No sound from radio, all radio and CD functions seem to work. See procedure # 1. - Check supply-line fuse to amplifier and all ground connections.
^ Unit cuts out at loud volumes. See procedure # 1.- Make certain ground connection is good. A high resistance across a loose ground connection can cause a voltage drop. The voltage drop gets worse when more current is pulled across the connection which causes the amplifier to be starved for power and shut off.
^ All channels intermittent. See procedure # 1. - Check all connections for loose or faulty contact.
^ Alternator noise. - Almost always a faulty ground. Check behind radio.
^ Subwoofer control does not illuminate. - Check ground connection behind radio and lamp voltage connection at cigarette lighter.
2. Signal wiring problems:
^ Individual channel faults. See procedure # 2. - May be either a bad part or more commonly a bad connection or cable short.
^ Intermittent channels. See procedure # 2. - Usually a loose connection. Be sure to test drive vehicle over bumpy roads to help weed out the cause.
^ System thumps repeatedly but does not turn on. See procedure # 2 first, then procedure # 1 if problem persists. - Usually the result of a short circuit in a speaker wire, the thumping is a result of the amplifiers circuitry protecting itself from the short.
^ Low or no subwoofer output. See procedure # 3.
3. Component problems:
^ No sound, all channels. See procedure # 1 - Possible faulty amplifier. Check for power supply problems first.
^ No radio operation. - Possible faulty radio. Check supply fuses first.
^ CD malfunction or skipping. - Possible faulty CD changer or Data cable.
^ Defective speaker. See procedure # 2. - Usually results in no sound or severely distorted sound from one speaker only. If more than one speaker is at fault with the identical symptoms the problem is likely to be with either the radio or amplifier.
Recommended tools:
In addition to the common hand tools required for access to the various components, music system troubleshooting will be greatly simplified with the following:
^ Digital Multimeter - meter should be capable of measuring DC voltage, DC current, and ohms with .1 ohm resolution.
^ High Efficiency Walkman-type headphones with adapter cable as shown in Fig. 1. - Unlike earlier model year units, the radio used is not capable of driving speakers, therefore, you cannot hook a speaker to the radio to test its output. Headphones however, can be driven to adequate levels for testing directly from the radio output.
Procedure # 1
Symptom: NO SOUND, or intermittent operation. All radio controls seem to operate correctly (unit lights up, display reads correctly etc.)
Likely causes: No power supply to amplifier or radio - check vehicle fuses first! Bad ground connection to amplifier or radio - follow steps below. Defective amplifier circuitry - follow steps below. Defective radio circuitry - follow steps below.
Unlikely causes: Speakers - it is not likely that all 7 speakers failed at the same time Subwoofer control - this should not affect the 4 main channels
Procedure:
1. Set radio as follows:
Source - Cassette Volume - center of rotation Bass, Treble, Balance, Fader. - FLAT Subwoofer level - center of rotation.
Check power connections:
2. Check that the Red LED on the amplifier is illuminated when the radio is turned on. If not, measure pin # 6 of the 12p connector. The voltage should be 12V with the Radio on, if it is not see step 3a. If 12V is present, see step 3b.
3a. Check for 12V at pin # 5 of the 8p connector at the rear of the radio. If there is no output, the radio is defective and is not sending the turn-on signal to the amplifier. The radio should be replaced. Before connecting a new radio, check continuity of this wire to vehicle ground, there should be no connection. If there is output at the radio end but not at the amplifier end, or the wire is shorted to vehicle ground, there is a problem somewhere along the body harness assembly. Refer to Land Rover documentation for routing and connector locations.
3b. Check for 12V at pin # 5 of either or both of the connectors to the amplifier. Also check for a good ground connection at both pin # 12 of the 14p amplifier connector and pin # 9 of the 12p connector. A good ground is defined as one with less than 0.3 ohms when measured between the connector pin and the vehicle chassis. If 12V is not present on the appropriate pins, either the vehicle fuse is blown, or there is a fault in the vehicle wiring. If the ground connection is faulty, the problem is also in the vehicle wiring. Refer to Land Rover documentation for routing and connector locations. If all voltages measure correctly, and the LED is still not illuminated, the amplifier should be replaced.
NOTE:
It has been determined that a condition exists in early production vehicles which may cause the amplifier to be damaged. If the LED on the amplifier does not illuminate, but voltage is correct on all power, ground and remote trigger connections, please contact Land Rover North America for information on any applicable service bulletins. Please have the V.I.N. available.
Check audio circuit output:
4. Using the headphone testing described under recommended tools, insert the GND side test probe into pin # 7 of the 12p amplifier connector. Insert one of the remaining probes into pin # 3 and the last probe into pin # 2. Operate the radio while listening to the headphones and confirm that you have proper output from the front two channels of the radio. If there is a signal here, refer to step 5a. If there is no output at this point, refer to step 5b.
5a. Turn the radio volume down and connect your GND probe to pin # 8 of the 14-pin amplifier connector and both of the other probes to pin # 1. Make this connection with the amplifier still connected to the vehicle harness. Raise the volume slowly until you hear sound. If there is no sound, replace the amplifier.
5b. Remove the radio from the console so that you may obtain access to the 10p connector at the rear of the radio. Connect the GND side probe to either pin # 4 or # 6 and the remaining probes to pins # 3 & # 5. If there is output present here, but not in the rear of the vehicle, there is probably a break or short in the under-body harness assembly. If there is no output directly from the radio, the radio is at fault and must be replaced or repaired. Refer to Land Rover wiring documentation for Information on the under-body harness routing and connectors.
Procedure # 2
Symptoms: NO SOUND OR DISTORTED SOUND FROM ONE OR MORE SPEAKERS. ONE OR MORE SPEAKERS INTERMITTENT
Likely causes: Loose or shorted connection between radio and amplifier - follow steps below.
Loose or shorted connection between speakers and amplifier - follow steps below.
Shorted connection between crossover network and speakers in front door. follow steps below.
Defective radio or amplifier. - follow steps below.
Defective speaker or crossover network. - follow steps below.
Dirty or worn tape head - see if problem exists with CD and FM sources also!
Unlikely causes: Fault in power or ground wiring. - this would affect all channels Fault in CD changer and data cable.
Procedure:
1. Set radio as follows:
Source - Cassette
Volume - center of rotation Bass, Treble, Balance, Fader. - FLAT
Subwoofer level - center of rotation.
Identify problem channel(s):
2. Use the radio BALANCE and FADER controls to listen to one channel at a time. Note each channel which exhibits a problem. If the problem exists in either of the front speakers listen carefully to both the 4" midrange speaker and the tweeter to determine if the problem exists in one but not the other. If the problem exists in midrange or tweeter only, the fault is most likely caused by either a faulty speaker or to a connector or cable fault between the crossover and the affected speaker - go to step 3b. If the problem exists in all speakers on a given channel, go to step 3a. If an identical problem exists in both Front and Rear speakers on the same side of the vehicle, it is likely that the problem is in the radio itself and not in the system wiring.
3a. Disconnect the 14p connector from the amplifier. Refer to the chart and measure the resistance between the connector pins of the faulty channel. The value should be approximately 4 ohms (+/- .5). Also measure the resistance between each of the pins and vehicle chassis. The meter should show no connection to vehicle ground.
If any pin shows a connection to ground, there is an unintentional short somewhere in the wiring between the speaker and the amplifier. First unmount the speaker and repeat the resistance tests with the speaker still connected. If the measurements are OK, the wiring is being pinched or shorted somewhere when the speaker is in position, examine the area behind the speaker carefully to identify the interference. Pay particular attention to the area near the speaker's terminals. If the problem remains, disconnect the speaker and repeat the resistance measurements again. If the problem is now cured, the speaker is defective and should be replaced. If you still show abnormal readings with the speaker disconnected on the rear speakers or subwoofer, the problem is most likely in the body harness assembly. Refer to Land Rover wiring information for routing and connector information. If the abnormal reading is in the front speakers, Go to step 3b before assuming the wiring is faulty.
3b. Front door speaker. Remove the suspected speaker from it's original location and swap it with the like speaker from the opposite side. If the problem moves with the speaker, it is faulty and should be replaced. If the problem stays with the location, disconnect the crossover network from the vehicle harness. This is done by disconnecting the two purple crossover wires from the black and black/white vehicle wires. This connection should be accessible through the front 4" speaker opening.
Once the crossover is disconnected from the vehicle, make the resistance measurement described in step 3a for the appropriate channel. if readings are abnormal, the problem is almost certainly in the vehicle body-harness assembly.
If the readings are normal, reconnect the 14p connector to the amplifier, connect a known good speaker to the black and black/white wires and listen to the system. If the sound is now faulty, but the resistance readings were OK, it is most likely that the amplifier is defective. It should be replaced through the a/d/s/ exchange program.
If the sound is clear disconnect the 2p connector which connects the tweeter to the crossover and measure the resistance between the pins on the side of the connector leading to the tweeter (black and red wires). The meter should read about 3.6 ohms and no pin should show any connection to vehicle ground. If you get an abnormal reading here, remove the tweeter and repeat the measurements. You should now show no connection either between the pins, or from either pin to vehicle ground. An abnormal reading here indicates a flaw in the wiring to the tweeter-mounting bayonet, follow the wiring as it travels between the connector and the bayonet and look for pinched or cut wires. If everything looks correct up to this point, but the problem persists, the crossover network is probably faulty and should be replaced.
Procedure 3
Symptom: IMPROPER SUBWOOFER OPERATION (No sound, Low level, Distortion)
Likely causes: Improper radio control settings. - set radio controls to "FLAT"
Fault in subwoofer level control wiring - follow steps below.
Defective amplifier - follow steps below.
Defective Subwoofer - follow steps below.
Unlikely causes: Faulty radio or CD changer
Faulty power or ground connection - (except in cases where the problem only occurs at high volume, a bad connection can cause the amplifier to lose power only when it draws high current as it does at high volume levels.)
Procedure:
1. Set radio as follows:
Source - Cassette or CD
Volume - center of rotation Bass, Treble, Balance, Fader - FLAT
Subwoofer level - center of rotation.
2. Turn the system on and listen carefully to the system while you rotate the subwoofer level control from minimum to maximum level. Assuming you have any subwoofer output at all, the output should vary smoothly from virtually no subwoofer output in the minimum position, to slightly too much output in the maximum position. If the operation of the bass control is reversed (i.e. max. output at min. rotation) the connector at the rear of the subwoofer level control is on upside-down. Reverse the connector and operation should revert to normal. If output varies, but does not do so very smoothly, the control is at fault and should be replaced. This is also the case if rotating the control causes scratchy or interminent operation. If output varies, or there is no output, go to step 3.
3. Disconnect the 12p connector from the amplifier. Measure resistance between pin 11 and pin 12 of the vehicle-side connector. The resistance should read almost 0-ohms when the subwoofer control is adjusted to maximum, and approximately 10,000-ohms when the control is at minimum. Also measure the resistance between pin 10 and pin 12 of the connector, now you should get a near 0-ohm reading when the control is minimum, and near 10,000-ohms when the control is at maximum. Reconnect the 12p connector to the amplifier. If any readings are abnormal, go to step 4a.
If all readings are normal, disconnect the 14p connector and measure the resistance between pin 6 and pin 13 on the vehicle-side connector. You should get a reading of approximately 3.8-ohms. Also measure between pin 7 and pin 14. You should get the same reading. (Make certain the 4p subwoofer-input connector is fully seated for these measurements). If either of these measurements are not correct, you probably have a faulty subwoofer. Either the subwoofer driver is defective, or a wire has come loose within the cabinet. Refer to Land Rover for information on repair or replacement of the subwoofer. Unlike the 1991 S.E. and 1992 systems, the subwoofer is not an a/d/s/ part and should be ordered through conventional Land Rover channels.
If all of the readings throughout step 2 are normal, go to step 4b.
4a. Remove the subwoofer level control from the dash and disconnect it from the cable. Bend a metal paper-clip into a narrow "U" shape. With the system playing, insert the clip into the rear of the 5p connector so that it jumpers contacts # 3 and # 4 as shown.
If you have maximum bass with the jumper in place, the subwoofer level control is defective. If there is still no bass, leave the control disconnected and repeat this test at the rear of the vehicle by inserting your jumper-clip into pins # 11 and # 12 of the 12p connector with the connector still connected to the amplifier and the system playing. if you have bass with the jumper in place, you have narrowed down the problem to either the under body harness or the subwoofer control link harness.
The two harnesses are connected together through a 3p connector in the cavity behind the radio. Inspect this connection to make certain it is not faulty. Refer to the drawing of the subwoofer link harness and measure continuity from end to end of each of the connections, If a fault is found in the harness, repair or replace it. If no fault is found, the problem is in the under-body harness assembly. Refer to Land Rover service documentation for information on this harness.
4b. Reconnect any connectors you may still have disconnected. Use the stereo headphone test jig described in Recommended tools by connecting the GND (black) test probe to pin # 10 of the 12p amplifier connector and one of the red probes to pin # 11. With the system playing, you should hear signal in the headphones. Operate the balance and fader controls of the radio to confirm that all four channels cause signal to be present at pin # 11.
If any or all of the channels show no output at pin # 11, replace the amplifier. If this test is OK, adjust the subwoofer level control to maximum, jumper pins 11 and 12 with a paper-clip as described in step 4a. Disconnect the 4p subwoofer-input connector. Connect your headphones between pin # 6 and pin # 13 of the 14p connector and listen for signal. (Note that the signal at this point only contains extremely low bass signals which may be difficult for some headphones to reproduce so you will have to listen very carefully. If your headphones make it difficult for you to hear the bass, you can substitute a speaker for this test in place of the headphones. You will not hear much bass from an unmounted speaker in this test either, but you can observe the cone to confirm that it is moving.) Repeat the test on pins # 7 and # 14. If there is no output in either or both of these tests, replace the amplifier.
If everything tests well to this point, it is likely that one of the two channels of input to the subwoofer is connected in opposite polarity. Refer to Land Rover wiring information and inspect each connection at the 14p amplifier connection and the 4p subwoofer connector for errors. If everything looks correct, the error is within the subwoofer cabinet. Refer to Land Rover for instructions to repair or replace the subwoofer.