Why do I not have any lights inside my 2000 venture

Question edited for clarity.

Fuses 4 and 8, but there is also a relay involved.

Fuse Box Diagram Mercury Mountaineer (1997-2001)

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Here you will find fuse box diagrams of Mercury Mountaineer 1997, 1998, 1999, 2000 and 2001, get information about the location of the fuse panels inside ...

Mercury Mountaineer (1997 - 2001) - fuse box diagram

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Aug 11, 2018 - Mercury Mountaineer (1997 - 2001) - fuse box diagram. Year of production: 1997, 1998, 1999, 2000, 2001. Passenger compartment fuse panel.

Mountaineer » Fuse Diagram

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Fuse Box Diagram Mercury Mountaineer; engine 4.0 L Cologne V6 and 5.0 L Windsor V8 (1996, 1997, 1998, 1999, 2000, 2001)

Has it been reprogrammed at the dealer? This will have to be done for the pcm to register the tcm

Perhaps you need to start with fog light problem I am guessing we do not know for sure the switch was the cause, if you can remove them from the equation. When checking for shorts make sure you check light bulbs to,
Next, since the multi function switch was the next step in your problem solving, I suggest you remove the new switch check out all wires to the connector, be especially careful to make sure none of wires have pulled out or partially pulled out of the connector. Let me know when you finish this then we can move on to continuity testing.
My best guess is the connector as it is common to both your fog light and multi-function switch,
Above all don't let it get to you, these problems can be frustrating but they also can be interesting and fun especially with the right assistant

If it keeps blowing and all wiring and grounds are OK. The issue is in your multi function switch. Replace your switches

first does he have battery cables tight and in right spot red cable goes to pos on battery and black cable goes to neg on battery and make sure nothing came unhooked or broke or loose on eletrical box

Lights intermittent can be caused by switch or relay. Try swapping the Low Beam relay with another similar relay (horn relay is a good choice) to see if that resolves it. These relays are in the Junction Block--may be under the hood or in the car but not in the big box by the battery). If this doesn't fix it, the problem is likely the headlamp switch.

Horn coming on is usually caused by a broken switch or stripped wire insulation inside the steering column. You would usually have to take the steering wheel off to fix it, and this requires special tools; however, if the problem happens to be under the steering column shroud, you may be able to fix it without taking off the steering wheel. Take the shroud off and see if you can follow the black/red horn wire. Follow it as far as you can to check for stripped insulation contact with any metal. If you lights switch is bad, you can also change that while you have the shroud off.

Please let me know if you have questions.

Wand Removal & Installataion

1. Disconnect and isolate the battery negative cable.
2. Remove the knee blocker from the instrument panel.
3. Remove the three screws that secure the lower steering column shroud to the upper shroud.
4. If the vehicle is equipped with a standard non-tilt steering column, loosen the two upper steering column mounting nuts. If the vehicle is equipped with the optional tilt steering column, move the tilt steering column to the fully lowered position.
5. Remove both the upper and lower shrouds from the steering column.

Fig. Steering column shroud removal for the Cherokee

1. Remove the two screws that secure the multi-function switch water shield and bracket to the top of the steering column.
2. Remove the one screw located below the left multi-function switch control stalk that secures the multi-function switch water shield and bracket to the steering column.
3. Gently pull the lower mounting tab of the multi-function switch water shield bracket away from the steering column far enough to clear the screw boss below the left multi-function switch control stalk.
4. Lift the water shield and bracket with the left multi-function switch off of the left side of the steering column far enough to access the two instrument panel wire harness connectors for the left multi-function switch.
   NOTE If the vehicle is equipped with the optional tilt steering column, lifting gently upward on the tilt release lever will provide additional clearance to ease left multi-function switch removal.
   
5. Disconnect the two instrument panel wire harness connectors from the left multi-function switch connector receptacles.
6. Remove the left multi-function switch and water shield from the steering column as a unit.
7. Gently and carefully remove the water shield from the switch by pulling it over the hazard warning switch button and the left multi-function switch control stalk.
8. 
   

To install:

1. Gently and carefully install the water shield onto the switch by pulling it over the hazard warning switch button and the left multi-function switch control stalk.
2. Position the left multi-function switch and water shield near its mounts on the steering column as a unit.
3. Reconnect the two instrument panel wire harness connectors to the left multi-function switch connector receptacles.
4. Position the left multi-function switch onto its mounts on the left side of the steering column.
   NOTE If the vehicle is equipped with the optional tilt steering column, lifting gently upward on the tilt release lever will provide additional clearance to ease left multi-function switch installation.
   
5. Position the lower mounting tab of the multi-function switch water shield bracket to the steering column screw boss below the left multi-function switch control stalk.
6. Install and tighten the one screw located below the left multi-function switch control stalk that secures the multi-function switch water shield and bracket to the steering column.
7. Tighten the screw to 10 inch lbs. (1.1 Nm).
8. Install and tighten the two screws that secure the multi-function switch water shield and bracket to the top of the steering column [Tighten the screws to 20 inch lbs. (2.2 Nm)].
9. Position both the upper and lower shrouds onto the steering column.
10. Install and tighten the three screws that secure the lower steering column shroud to the upper shroud. Tighten the screws to 18 inch lbs. (2 Nm).
11. If the vehicle is so equipped, tighten the two nuts that secure the non-tilt steering column upper mounting bracket to the dash panel steering column support bracket studs. Tighten the nuts to 200 inch lbs. 22 Nm).
12. Reinstall the knee blocker onto the instrument panel.
13. Reconnect the battery negative cable.

FUSE 7 - 15 AMP FUSE.IF FUSE OKAY.YOUR BRAKE LIGHT SWITCH IS FAULTY OR MULTI FUNCTION SWITCH IS BAD.BECAUSE BRAKE LIGHT SWITCH ON SAME CIRCUIT WITH MULTI FUNCTION SWITCH.

is the anti-theft light flashing? if not, its not a anti-theft problem. did you check in neutral? you should be able to bypass the relay. you cant do anything without a wiring diagram for the starter

First project, have the Battery Charged for 24 hrs. then Tested. This is the Heart of the system, without it known to be in good condition, nothing else functions properly.
Regards,DT

The venture runs without problems, but then off-key upside down but nothing works, even though the battery is full. you only hear something like relay switch and then dead