Radio pops shuts off, lights dim up and down, bells ring, several lights on dash off and on, I pulled blinker to turn on bright lights and the car immediately down shifted.

there is a regulator for the display brightness, you may have it turn'd down or it has stopped working;. it controls the brightness at which the dash lights are. usually has a speedo sign on it. goes up and down. it works with the main light and is conecter to them on the same lighting board if it has gone then a new light swtch control switch will be needed.

I would first concentrate on all ground cables, straps etc going to firewall, battery, engine etc.

Could have connection issues at the BCM - body control module , lose ground . The BCM controls all the thing's your have problems with .
Turn Signal Lamps
When the turn signal switch is place in either the right or left turn position, the turn/hazard request circuit is pulled low, through a resistor. The body control module (BCM) uses the resistors to determine if the left or right turn signals have been requested. The BCM then supplies an ON-OFF voltage to the turn signal lamps and turn signal indicator on the selected side of the vehicle. The turn signals receive a ground at G101, G401, or G403.

When the ignition switch is turned to the ON position, the vacuum fluorescent (VF) display (radio) turns on at maximum brightness. When the park lamps are ON all incandescent back lighting turn ON at the dimming level indicated by the IP dimmer switch. At the same time all vacuum fluorescent (VF) displays dim to match the indicated dimming level. When the headlamp switch is placed in the PARK position, the park lamp supply voltage circuit provides an input to the body control module (BCM). The BCM then supplies voltage to the instrument panel dimmer switch through the instrument panel dimming lamps control circuit. The setting of the instrument panel dimmer switch determines the amount of voltage that the instrument panel dimmer switch supplies to the BCM through the instrument panel dimming lamps low reference circuit. The BCM then sends a pulse width modulated (PWM) voltage to all the interior lamps. All the vacuum florescent (VF) and incandescent back lighting lamps are provided a specific voltage and are then grounded. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting turn on at the dimming level indicated by the IP dimmer switch. When the IP dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from Minimum intensity to maximum brightness in response to the IP dimmer switch.

Engine Coolant Indicator(s)
LOW COOLANT LEVEL
The IPC illuminates the low coolant warning indicator when any of the following occur:
• The BCM detects a low coolant level condition for at least 30 seconds. The IPC receives a class 2 message from the BCM requesting illumination.
• The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds .

The thing to do first would be to hook up a factory or professional type scan tool an check for Instrument cluster or BCM DTC'S - diagnostic trouble codes . Then checking connection 's at the BCM , testing power an grounds .


ECM Inputs and Outputs Diagnosis

Open Circuit Detection Wiring Diagram 1

Take in to have the chargeing system check out on it,

check for earth lead at battery is not broken/

wht ??

battery cable is dirty or lose

Check to make sure the DOME light switch on the dash ( adjust brightness of dash lights also ) is off ( usualy a wheel not a nob) roll up for on down for off next time driving adjust dash brightness with this switch

Not without voiding the warranty.

possibly the dimmer switch on the floor? happened on my 91 half ton dims didnt work but brights did and then they cut out altogether. a little water goes a long way