How to trouble shoot no interior light 1998 masda mpv 3.0

Top of the pic. Engine compartment. Left rear near firewall.

Check for spark. Also injectors could be clogged. Not enough information to tell really.

Naturally...when you have a serious problem somewhere in your AC system.

Engine

Check switch and ballast resistor and fuse.

Here is the diagram courtesy of 2carpros.com

take the bulb out and get a multimeter and check to see if there is voltage going to it make sure u have the switch on for the light

SOUNDS LIKE AIR BYPASS VALVE STUCK

BTN stands for Body/Tail/iNterior. It protects the HAZARD, ANTENNA, ROOM, STOP, ILLUM and ABS fuses in the cabin fuse box, which in turn protect the hazard lights, antenna, ECU memory, brake lights, tail lights, ABS, power locks, clock, horn, illumination, stereo, HVAC, interior lights and alarm. __________________

Hello Jtarchala,

Interesting (and doubtless very vexing) trouble...

I always recommend that an OWNER beg, borrow or BUY
the FACTORY+WORKSHOP+REPAIR manual..
but as that is not always an option...

I like to point out where FREE wiring diagrams and
TECHNICAL SERVICE BULLETINS (TSBs) can
be accessed (on BBB Industries website (registration
is required... as these are real documents))... for popular
USA Market vehicles.

FREE diagrams & TSBs
BBB Industries Premium Alternators Starters Power Steering Products

I noticed the Manual switch (dash) was assumed to be the trouble... out of curiosity I tried looking up your switch...

Please note: while totally UN-SCIENTIFIC.. when I find
multiple BRANDS of a particular switch STILL (plentifully) available ...

I CONSIDER I have FOUND A PROBLEMATIC area ...

GUESS WHAT... Your switch is WIDELY AVAILABLE in large numbers (quite popular (a huge clue)..

Check them out: ROCKAUTO (examples)
1998 JEEP GRAND CHEROKEE 5 9L V8 Headlamp Switch RockAuto

Product detail:
More Information for OMIX ADA 1723429

Notwithstanding that screaming clue...
Each door and the TAIL-GATE also have contacts
which can jointly or singularly contribute to the problem.

Putting some body sealant (or play-dough) on the tip of each plunger... ( I would simply remove THEM and TAPE OFF the
connectors to TROUBLE-SHOOT)...

Again: hugely popular parts
1998 JEEP GRAND CHEROKEE 5 9L V8 Door Jamb Switch RockAuto

Rear tail-gate (switch)
More Information for STANDARD MOTOR PRODUCTS AW1048

Door contact (examples)
More Information for STANDARD MOTOR PRODUCTS DS875

Actually... including the courtesy timer module... this is a fairly complex circuit to trouble-shoot...

I hope I am helping.

I like electronics, circuitry (etc.)... Please feel free to comment
me or EVERY "FIXER" for more depth... & HAPPY HUNTING.

Carnac the Magnificent