Where is brake fluid reservoir 1991 dodge spirit

replace the brake light sensor manual will state where it is located

things that have to be checked during a brake replacement process
the caliper pistons have to move back easily when fitting new pads
the caliper body has to move freely on the mounting pins to allow the centralization on the disc rotor
the brake bleeder nipple has to be opened when pushing the pistons back as the displaced fluid build sup pressure in the reservoir
check that the fluid level in the reservoir is not above the full line
check the brake master cylinder is operational and compensating ports are not blocked
basically the problems is that the pads are in contact with the disc and that is generating heat. that heat expands the brake fluid that has to be allowed to flow back to the reservoir
if the expansion of fluid is prevented either by over full reservoir or faulty mastery cylinder preventing the free flow back to the reservoir then the expansion applies the pad more tightly to the disc which in turns creates more heat and more expansion of the fluid
At this point and before you do anything else ,my steps would be to flush the system out using metholated spirits by filling the reservoir and then bleeding each wheel until clear fluid came out
when this is accomplished any black junk in the system is removed
fill the reservoir with new brake fluid and repeat the bleeding process until only brake fluid comes out
Metholated spirits is compatible with brake fluids and is recommended for the purpose
having cleaned out the system and ensured the free movement of the calipers on the mounting pins the pads should be in light contact with the discs and hubs should spin free after brakes are applied and released
In practice pads always touch the disc as there is no method of pulling the ads back and it is the air friction between pad and spinning disc that gives a minute clearance when travelling and if that ability is not allowed then the problems that you have will result

ok check your brake fluid at the master cylinder i could very well be low

Ask a dodge parts dealer.

Your brakes are worn, low fluid, faulty master or leaking slave. In any case it's unsafe to drive. Your brakes could fail at any time without warning!

hi 1st thing to check is the brake fluid level is topped up as the reservoir has a sensor fitted to cap so as brake pads/shoes wear the fluid is displaced from reservoir to compensate cylinders hence fluid level falls and puts light on as you brake ? also possibility is that your pads may be fitted with low brake pads warning indicators/wires which also puts same light on as you brake and goes off when you let off to accelerate ? check both of these possibilities if you req more help/advice by all means come back with info

Check the brake fluid. It may be just low enough to occasionally turn the light on as you hit bumps and it sloshes a little. Add a little brake fluid to the reservoir and check the brake pads all around.

Check the fluid the brake master cylinder reservoir and fill to line, if the light doesn't go off u have a mechanical problem with the brakes or the park brake switch is sticking on..

Taken from Haynes repair manual. I used these instructions myself to replace starter motor on my 1989 Dodge Spirit after nearly going berserk at three attempts to remove it without wanting to look it up in book.
1)Detach the negative battery terminal. 2) Working from above the engine, remove upper mounting bolt and nut to starter. (Access is accomplished this way: stand on driver-side fender and look down at brake fluid reservoir. Just below and beyond the brake reservoir you will see a vent hose. Disconnect hose & remove. Now you will see the starter motor from above view. You will be able to see a mounting bolt and a nut connecting starter to engine just above the starter (facing brake reservoir). Remove (1) bolt & (1) nut first, then raise vehicle and suport on jackstands. Then go underneath the vehicle and remove the remaining lower mounting bolt (1) on the starter. Label wires then detach them from starter. Now you can remove the starter. If you find it a tight squeeze, you may want to remove or swing the transaxle on that side for additional access, although that is not mentioned in manual (but I did it). It just gives you more room, but does not seem absolutely necessary. 3) Installation is reverse of removal.
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bad ground on battery to engine block,use jumper cable from negative to a metal bracket on engine and see if that resolves issue if so get a new ground cable.