RE: please help me
In a 1998 Mark VIII the fuses are # 28 in the instrument panel fuse box and # 4 & 13 in the engine compartment. The # 3 fuse in the engine compartment is the one that directly connects the compressor to the battery. It goes through a relay which is controlled by the Air suspension/EVO steering module located on the right side of the cowl (down where the passenger's feet are). You could have shorted out something in there. Also make sure the switch is on in the trunk, which if it is off, should give you a message in the display. Turn off the switch and see if you get that message. Does your speedometer work? That module feeds the speedometer through the module interlink.
If you really want to get into it:
Remove the right hand side cowl cover by lifting the front of the right hand side door sill cover at the front. Slide the little "foot" of the cover towards the inside of the car gently without breaking it. Let go of the sill cover, then the little "foot". When you let it go, it will rest on the top of the sill. Then pull the cover to the rear removing the hidden push pin and releasing the cover. If you look above the connectors along the bottom, you will see a small module with two connectors, they are called C204 & C205. C204 is black and C205 is Gray. Remove the battery ground connection (8mm 1/4" socket if stock) and then remove the two connectors on the module. by pushing on the release tabs on the back side and pulling down. You may have to remove the module to do this (1 screw and pull rearward). It is not hard to re-install the module. Now, holding both connectors together, so they look like two long Us |_20_____205______11_||_10_____204______1_| 204 is numbered backwards with pin 1 being on the lower right, so it goes right to left 1 through 10, and then it continues on C205 the same way only 11 through 20. on the top it is the same. C204 on the top starts on the right as pin 21 through pin 23, then the release, then 24 through 26. It continues on to C205 the same with pin 27 on the top right through pin 29, then the release, then 30 through 32.
After disconnecting the connectors from the module, put the battery ground back on, temporarly. On C204 use a 12 volt meter to make sure there is battery power on pins 1 (Dark Green/Yellow wire) & 21 (dark Green/Yellow again). and pin 4 (Purple/Orange wire), if the ignition switch is in run. Do this by clamping your meter black wire to a known good ground and the red probe wire to the numbered pins. Next, change the meter to read the smallest resistance it can and check C205 pin 32 (Black/Light Green wire, so the meter deflects back to zero ohms. Do the same with C204 pin 23 (Black/Light Green). You are checking the grounding system. Check C204 pin 5 (Black/Light Blue)for 0 volts if a door is open. Check C205 pin 11 (Brown/Pink) for 0 volts if the rear air suspension switch is on. Test the switch both on and off. One way you should register +12 volts and the other, 0 volts. Leave the switch in the up position. From there, you can test the speed sensor by checking the resistance between C204 pins 3 (Dark Green/White) and pin 23 (Black/Light Green). Then go to the sensors, again checking for resistance, Check for +12 volts on C205 pin 28 (Pink/White) first. Connect the black probe to C204 Pin 7 (Pink/Black) and the red one to C205 Pin 28 (Pink/White) See if there is a large (+12 volts) or small amount of voltage there. (It depends on where the car is sitting (as far as height). Keep the red probe in C205 pin 28 and change the other probe from C204 pin 7 to pin 8 (Tan) Same thing. Now change the same probe to C204 Pin 9 (Orange/Black). Now change the red probe from C205 Pin 28 to C205 Pin 10 (Black/Pink) and check the same three pins on C204 the same way, only this time, you are looking for resistance. The resistance amount is not critical. You are just looking to see if the sensors are connected and not open.
From there, clip your black meter lead to a good ground. Now check with your red probe C205 Pins 14(Light Green/Orange), 15 (Orange/Red), 16 (Purple/Light Green), and 17 (Light Blue/Black). Make sure the resistance is low on each pin. That checks out the solenoids on each spring. You could put 12 volts to it, but it may just lower the car even more and you don't want to do that.
Now check the vent solenoid by again keeping the black probe wire to ground and connecting the red one to C205 pin 30 (Pink wire). Make sure the resistance is low. Now keeping the black wire in the same place, check the compressor solenoid by putting the red probe on C205 Pin 18 (Dark Blue/Yellow) Again, look for a low resistance.
If everything is OK up to now, Check out the compressor, with a short wire between C204 pin 1 or 21 (both Dark Green/Yellow) and quickly connect it to C205 pin 18 (Dark Blue/Yellow). You should hear the compressor kick in. If not, you will have to get into the compressor and find out why it is not running. Either the relay is bad, or the compressor motor is bad. They are near one another in front of the passenger's side front wheel. If you can get to the relay, Check pin A (Black/Yellow) for +12 volts (or battery voltage which may be higher) If that is present, short out pins A (Black/Yellow)& B (Pink/Orange)with a heavy wire, that should start the compressor. If not, the compressor is probably bad or the wiring is bad. From there, you need to either put everything back where it goes and make a choice either take it to your dealer to have him look at it with the NGS tester, or replacing the compressor yourself. If you decide to take it to your dealer, first remove the ground cable from the battery and then reconnect the two connectors to the air suspension/EVO steering module. You can leave everything else open, because the dealer will probably take it apart up to that point anyway, but with the NGS tester, he can get any trouble codes that may help in repairs. But if the compressor runs, and everything else checks out, you did some damage to the module itself.
That's about as far as you can go without an NGS teaster and they are around $1,700.00.
Here are the complete pin outs looking at the connector from the front starting at C204 (bottom right) going through C205, then back to C204 (top right) then back to C205 on the top. (what a way to make a car)
The first color is the color of the wire, the second is a stripe or hash mark:
C204 Pin 1 (DG/Y) Battery Power
C204 Pin 2 (R) Steering wheel Rotation Rate Input A
C204 Pin 3 (DG/W) Vehicle Speed Input (+)
C204 Pin 4 (P/O) Ignition On Input (Hot In Run)
C204 Pin 5 (BK/LB) Door Open Input
C204 Pin 6 (GY/R) Diagnostic Input
C204 Pin 7 (PK/BK) Left Front Sensor Input
C204 Pin 8 (T) Right Front Sensor Input
C204 Pin 9 (O/BK) Rear Height Sensor
C204 Pin 10 (BK/PK) Height Sensor Ground
C205 Pin 11 (BR/PK) Air Suspension Switch Input
C205 Pin 12 (DG/LG Warning Message Feed to Message Module
C205 Pin 13 (O/LB) Diagnostic Input
C205 Pin 14 (LG/O) LF Air Spring Solenoid Output
C205 Pin 15 (O/R) RF Air Spring Solenoid Output
C205 Pin 16 (P/LG) LR Air Spring Solenoid Output
C205 Pin 17 (LB/BK) RR Air Spring Solenoid Output
C205 Pin 18 (DB/Y) Compressor Relay Control
C205 Pin 19 (Y/LG) EVO Actuator Feedback (+)
C205 Pin 20 NOT USED
C204 Pin 21 (DG/Y) Battery Power
C204 Pin 22 (BR) Steering Wheel Rotation Rate Input B
C204 Pin 23 (BK/LG) Vehicle Speed (-)
C204 Pins 24, 25, 26, NOT USED
C205 Pin 27 NOT USED
C205 Pin 28 (PK/W) Height Sensor Power Output
C205 Pin 29 (LG) Diagnostic Input
C205 Pin 30 (PK) Vent Solenoid Control
C205 Pin 31 (LB) EVO Actuator Feedback (-)
C205 Pin 32 (BK/LG) Ground
Wire Colors:
BL = Blue
BK = Black
BR = Brown
DB = Dark Blue
DG = Dark Green
GN = Green
GY = Gray
LB = Light Blue
LG = Light Green
N = Natural
O = Orange
PK = Pink
P = Purple
R = Red
T = Tan
W = White
Y = Yellow
Good luck
