Compass Variation & Self Diagnosis, DE-Gaussing the Vehicle
COMPASS VARIATIONCompass variation is the difference between the earth's Magnetic North and True North. It is True North that is used on most road maps. The difference between the Magnetic North, and the geographical True North for your particular location, must be known to the compass. If the compass variation is not set, the owner may complain about driving on a north road, and his compass reading will be NE or NW.
To set the compass variation follow these steps:
1. With the vehicle running, point the it North by using a North/South road for reference.
2. Press the end of a paper clip into the hole on the passenger's side of the console (Prince), or the slot between the U.S./Metric and temperature button (T.R.W.). The display will show an N T (Prince) for two seconds, then show the temperature and direction; or an N (T.R.W.) will flash and stay on to indicate that the variation has been set.
COMPASS SELF DIAGNOSIS
If either of the compass units are not accurate, it is imperative that the compass be re-calibrated. ONLY after a re-calibration can you be sure that the diagnostic results are accurate.
(All Models Except "J" Body)
Begin the self-diagnosis of the system by turning the vehicle "Off".
While holding the "On-Off" and the English/Metric buttons down at the same time turn the ignition switch to the "Run" position.
The display will cycle between three numbers:
^ The variation number, when the compass portion of the display is blank.
^ The north calibration number and the letter N.
^ The west calibration number and the letter W.
Both the NORTH and WEST calibration numbers MUST be within plus or minus 30. If the calibration sequence was carried out properly, and the NORTH or WEST calibration number is in excess of plus or minus 30, there is an excessive magnetic influence near or around the compass area. If nothing is found, such as something magnetic in the overhead storage compartment, or a magnetic mount antenna, it would indicate the vehicle must be de-gaussed, or de-magnetized.
("J" Body Only)
A C1 reading during the first step of the calibration procedure for longer that TWO minutes is an indication of external magnetic influence. If nothing is found, such as something magnetic in the overhead storage compartment, or a magnetic mount antenna, it would indicate the vehicle must be de-gaussed, or demagnetized.
DE-GAUSSING THE VEHICLE
NOTE: REPLACING THE COMPASS MODULE WITHOUT DE-GAUSSING THE VEHICLE WILL NOT CORRECT THE CONDITION.
The tool used to de-gauss or de-magnitize the vehicle is the HAN-D-MAG, Model 220-S, available through Miller Tool under number 6029. Equivalent units are also available, but must be continuous rated for 110/115 volts and 60 HZ with a field strength of over 350 gauss at 1/4" beyond the tip of the probe.
In this de-gaussing procedure you will use the de-gaussing tool to contact the mounting screws in the overhead console area. It is important that you follow the instructions below exactly. The mounting screws are steel, and therefore aid in the de-gaussing of the roof panel, as well as the mounting brackets around the compass area.
1. Be sure the ignition switch is in the "Off" position before you begin the de-gaussing procedure.
2. Remove the map lamp lens caps and open the sun glass compartment to gain access to the overhead console mounting screws.
3. Plug the de-gaussing tool into a standard 110/115 volt AC outlet, keeping the de-gaussing tool at least 12" away from the compass area when plugging it in.
4. Slowly approach each of the console mounting screws with the plastic coated tip of the de-gaussing tool. Contact and hold the tip of the tool to each screw for at least TWO seconds.
5. With the de-gaussing tool still energized, slowly back it away from the screw until the tip is at least 12" from the screw head.
6. Repeat step 4 on all of the console mounting screws, and you will have completed the de-gaussing procedure.
7. After you have pulled away at least 12" from the last screw, remove the degaussing tool from the vehicle, and disconnect it from the electrical outlet.
8. Re-calibrate the compass.
NOTE: PRINCE CORPORATION HAS A SPECIAL TECHNICAL ASSISTANCE PHONE LINE FOR DEALERSHIP USE IN DIAGNOSTING UNUSUAL COMPASS/THERMOMETER PROBLEMS IN "E", "H", AND "S" BODY VEHICLES ONLY. THIS TECHNICAL ASSISTANCE PHONE
LINE IS: 1-800-922-7723, AND IS IN SERVICE DURING NORMAL BUSINESS HOURS, MONDAY THROUGH FRIDAY.
POLICY: Reimbursable within the provisions of the warranty
TIME ALLOWANCE:
Labor Operation No. 08-45-07-90 . . . . . . . . . . . . . 0.4 Hrs.
FAILURE CODE: 15 - Calibration
This Technical Service Bulletin contains a modified de-gaussing procedure for "J" body vehicles. File it with Technical Service Bulletin #08-14-87. The modified de-gaussing procedure entered production on May 11, 1987.
SYMPTOM/CONDITION
A "C1" reading on the compass that does not change during first step of the calibration procedure, or an "*" with the vehicle direction that will not change.
REPAIR PROCEDURE
This procedure involves de-gaussing the roof panel when the magnetic field in the roof panel exceeds the level allowable to calibrate the compass.
1. Remove three compass/console attaching screws and lower compass from mounting bracket.
2. De-gauss the bracket (Miller Tool 6029 or equivalent) thoroughly through the openings in the headliner, using the following steps:
a. Stay at least 12" away from the compass area when plugging in the de-gaussing tool.
FIGURE 1:
b. Touch de-gaussing tool probe to starting point (Figure 1).
c. Slowly trace around outer edge of bracket to ending point. (Probe must touch bracket.)
d. De-gauss rearward portion of bracket.
FIGURE 2:
3. De-gauss the roof panel on the outside of the vehicle over the compass area (Figure 2).
4. Reinstall the compass/console with the three mounting screws and de-gauss the screws.
5. Calibrate the compass per Technical Service Bulletin 08-14-87.
6. Set the compass variance per Technical Service Bulletin 08-14-87.
POLICY: Reimbursable within the provisions of the warranty
TIME ALLOWANCE:
Labor Operation No. 08-45-07-90 . . . . . . . . . . . . . 0.5 Hrs.
FAILURE CODE: 15 - Calibration