No power, dash or hazards hiace van

Hello. It seems your Toyota's power 'in feed cable' is 'burnt-out/corroded. It's also possible the battery terminals are corroded

What exactly is wrong with it? Start with the basics. Check the fuse. I think on that model the horn and hazard lights were on the same fuse so test your hazard lights are working. Check the wiring and connections are clean and shiny at the horn sounder itself. If you know how to use a multimeter you can check for signal from the switch with a helper pushing the horn button.

No dash lights? no warning lights? Then ignition is not being turned to ON. Check all your fuses. Recheck your replacement work. Battery cables clean and tight? Headlights work? If lights are bright, battery is good and cables are good, so key to ON should light up warning lights on dash. If not something up still with your ignition switch.

Check for power to the ignition switch via test light or better a multimeter, could be a blown fusible link, usually housed in engine bay , or faulty ignition switch...
Work your way forward from the battery, testing power to and through all fuses, connections.

Do the headlights or hazard lights work...

the signals work off of the hazard flasher. the hazards are wired to constant power.if you run a fused wire from the hazard switch to the battery it all should work.
somehow the hazard power source got lost.check that there is not a blown fuse in the fuse box. a starter solenoid draws a good amount of current.they may have blown a small amp fuse looking for a power source.
patching into a fuse box for power is not high caliber work.

Go through the basics.
1 Make sure the alternator is charging (operating properly) by measuring the voltage between earth (battery negative) and the live terminal. It should be greater than 13 volts, less than 15V.
2 Make sure the regulator is being excited. Most modern alternators need to have the dash light working in order to send a minute current to the alternator regulator to kick it into life. If the dash light is out, (fused) the alternator won't work.
3 If the voltage from the alternator live terminal is good, check the voltage at the battery. It should be between 13.5 and 14.8 Volts. If this reading differs from the reading at the alternator output, you have a wiring issue.
4 Wiring issues may include but is not limited to:
a) bad connection at the battery terminal
b) bad connection at the main fuse,
c) bad connection at the starter motor. Some vehicles pick up the main power from the battery cable at the starter solenoid.
d) broken wire, bad connections on the main power lead connection terminals.
Happy hunting!

Your charging system is not working correctly. Unlike most other vehicles, the alternator in yours does not have a built in regulator circuit. Some troubleshooting must be done to find the defective component. Most of this can be done with the vehicle still assembled.

First, check that you don't have a blown fusible link. In most newer cars, these will be in the underhood fuse panel, and look like giant fuses. If good, you will read very nearly zero volts and zero ohms when measuring between the positive battery terminal and the alternator output terminal. If either measurement doesn't read zero, find the loose connection, bad wire, or blown fusible link.

Next, check the ground connections to the engine, battery, and car body to make sure you don't have a bad wire or connection somewhere. Again, measure voltage and resistance between the negative battery terminal and all associated grounding locations. For a quickie test, you can rig a jumper cable between the battery negative terminal and the alternator case. If there is a spark when you make the connection, you have a bad ground somewhere.

If your battery is well connected to the alternator, the problem may lie in the control circuit. Most Chrysler alternators have two control wires that control the field coil. Some control the battery current and have constant ground supplied, and some have battery voltage applied and control the ground current. To test, disconnect the control connector and measure the voltage of both terminals with the ignition in the "off" and "run" positions. Make a chart of each terminal and its corresponding voltage.

Start the vehicle and measure both terminals again. If the terminals tend to be zero volts, except when the vehicle runs you have voltage on one terminal, you have a system where the computer controls battery voltage. If the terminals tend to be 12 volts when the ignition is on, then one terminal goes low when the engine runs, the computer controls ground current. If the voltages of one terminal change but not the other, this suggests a bad computer.

To do a go/no go test of the alternator unit, you can connect the control pins on the alternator with the control connector disconnected. Simply connect jumper wires to the two control terminals of the alternator. Connect one jumper to a known good ground, leaving the other jumper loose. Connect a voltmeter to the battery terminals or to the output wire on the alternator. Start the vehicle and briefly connect the second jumper wire to the positive battery terminal while watching the voltmeter. While the jumpers are both connected, the battery voltage should rise dramatically.If it doesn't, this suggests a bad alternator.

If all this sounds too complicated or dangerous, a good mechanic can perform a similar diagnosis in under an hour with definite results. Good luck.

check the battery and charging system

hazard lights left on ? check to see waht relay it is that is clicking anr read to see what it is for? hope this helps