Why is it missing fuse pins in relay section of fuse box?

Taco(ma)
not told engine runs car drives
not told blower dead on high.
we can not see your hands blinded in text box;.
is the blower dead on high
are the controls , climate controls or the old skool(sic) manual.
hands
under hood fuse box , 5oamp yes it is that.
under dash fuse box
or fiddling about on blower box side at the RESISTOR block.
yes fuses are tight for good reason,s.

that 50amp fuse in the schematic is marked in strange way.
a fuseable link maybe.
there is no reason to pull it first.
use a voltmeter, to both ends, 1 at a time and black lead of meter to NEG lug of battery both sides 12vdc is good fuse. heater turned on.
the heater relay dead, will make my test fails, due to leakage currents. and dead relay .
key off, battery neg lug pulled
measure ohms of fuse , directly must be 0 ohms.
what is wise if all is use the meter on the relay heater
measure volts on all pins of it , x4
the test is
Igntion must be on for heater relay to energize. and blower on., full


here is the relay tests.

super simple 1st test.
pin 5 ,= 12vdc , if not 5amp blown.
pin3 , 12vdc or relay is off line or bad.
pin1, 12vdc or ign1 fuse blown/
pin2, 0vdc if not the controller is malf''ing control switch not grounding this point

if all that passes the blower resistor block is bad, and super common.
but on high blower works ok? as high bypass the block.

I will post and not cover Rear AUX heater box. ok, and is and option

what part of this car has blower
is this HVAC blower failing on HIGH
is this manual version or climate control option.
fuse are blown in cab or in bay (engine)
fuses are first of high speed blower mode fails dead.
what IS A CKED ????? is see no hits in my ASE books on that part or device name in a car or a truck
2003 chevy tahoe , no engine /trans told. (this dictates fuse boxes)
my guess HVAC topic but no sure, what fan/blower or turbo this is.
climate control model has left and right controls and all differenet wiring max. differ.
fuse Hvac1, hvac-ECas, and fuse BOWER< yes 3 fuse must not be blown and the BCM is the brain here.
not scanning the PCM to see BCM errors is a huge error in testing
manual controls the resistor block uses a relay to send 12dc to he blower set to HIGH. all resistors bad ,high still works.

here are the 4 things to fail;
4 is good so 3 things, 2 fuses,
#3 is relay. to fail. a volt meter finds this easy for sure reading this page in the SM.below 3 pins on relay are at 12v.
so are pin F and G 12vdc if not input to them is bad.
not counting bad wires.,

HI/LO Freon switch is first or relay stays off line 5.7L V8 GAS OR DIESEL? 2 ARE DIESEL OF 3.
scan the PCM first. p0646?

THE PCM CUTS THE CLUTCH FOR MANY REASONS;
HI/LO SWITCH TRIPPED
CAB BLOWER DEAD
ENGINE OVERHEAT (OR SENSOR FOR THAT TELLING A BIG LIE)
ENGINE OVER LOADED RUNNING WOT.
EVAP CAR ICE UP SENSOR. TRIPPED.
FUSES.
NO SCANNING PCM WE MISS THE BOAT .
WAY TOO COLD OUTSIDE, SENSED.
ENGINE RAD FANS DETECTED DEAD.
CLUTCH IS BAD OR SHORT OR OPEN COIL
RELAY BAD.
THE NEW RELAY SHOWS 5 PINS. SO IS BIG CLUE THERE.
CAB FUSE BOX NOT ENGINE BAY
LEFT SIDE COLUMN OF RELAYS
TO9 LEFT SPARE RELAY,FOG, ASD ,CLUTCH
4 DOWN LEFT

Fuse number 27 in the underhood fuseblock supplies power to the cooling fan relay. If the fuse is good pull the relay and make sure there is power on one of the pins all the time. This will confirm that the relay is getting power from the fuse.

Two of the other 3 pins for the relay should have ground all the time. One is the main ground for the relay and the other is the power feed to the fan motors. If one is missing there is an open in the wiring. if both are missing than I would suspect a bad ground since the relay and the fans share the same ground.

Let me know what you find and I'll see what I can do to help you further.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

The blower motor relay in the auxiliary junction box under the hood is good ? All relays ? only one controls the blower motor ! The electronic automatic temperature control module turns it on by supplying a ground inside the module ! The 30 amp fuse for the blower motor is located in the under hood auxiliary junction box ! At the relay socket test for battery voltage at pins 30 an 86 ,power form 30amp fuse ! The other two pins 85 an 87 ,85 is circuit to the electronic temperature control module . You could test this part of the circuit too , with a test light or volt meter . But if no voltage to the blower motor ,could be the electronic temperature control module is bad ! VEHICLE RELAYS Operation Diagnosis

There is a relay in the under hood fuse box , blower motor relay .When switched to high it energizes the relay allowing power from the HVAC fuse /30 amp to flow direct to the blower motor. from pin 30 to pin 87 , if you look on the side of the relay there is a diagram .For all other speeds the current flows from the switch through the resistor through pin 87a to pin 30 on to the blower motor ! Check the HVAC fuse in the under hood fuse block .IF the fuse is good check for continuity between the fuse side with out B+ that means pulling the fuse and using a volt meter to see which side has power and checking the side that doesn't have power to pin 87 at the relay socket ! Probably a bad fuse or stuck relay . Pull that relay and try a different one. You can get wiring diagram at www.bbbind.com click on technical information ,then click on Technical Service Bulletins & Wiring Diagrams .then on next page go down to the bottom and click on I agree . next page click wiring diagrams ,then just fill in you vehicle information .then HVAC system . click on diagram, then you will see 7 links , click on the 5th one and that's the diagram for the blower motor circuit !

its all in the glove box, open it and read the operators guide.
see fuse section.
buy one or get one free on line, google for it.
its also in the FSM. book.
or at alldata.com

The Fans are controlled via Relay, and the PCM on newer cars controls that in complex ways.
the front fan is called the A/C condenser fan the rear fan is RAD fans.
the FSM coves the tests for each and ALL steps to find what is bad.
it only takes the FSM and DMM (voltmeter ) and 15min work to see who an what is bad.
(so we look at the relay, fuse good)
we check all 4 pins with a voltmeter. bingo we know.
ask more questions, can show drawings, after fuse are good.

There are two fuse boxes. A baqttery junction box under the hood on the drivers side and one inside on drivers side. Good luck.

Fuse/Relay

Location

Fuse Amp

Rating

Power Distribution Box

Description

1 60A** I/P Fuse Panel

2 40A** Blower Motor Relay

3 50A** 4 Wheel Anti-Lock Brake System

(4WABS) Module

4 30A** Power Windows, Power Moon

Roof, Power Seat

5 50A** Ignition Switch, Starter Relay

6 20A** Transfer Case Relay

7 - Not Used

8 20A** Air Suspension

9 40A** Air Suspension

10 30A** PCM Power Relay

1 10A* A/C Relay

2 30A* Heated Seats

3 30A* Heated Backlight

4 15A* Fog Lamps and Daytime Running

Lamps

5 4 3 2 1

10 9 8 7 6

12 11 10 9

8 7 6 5

4 3 2 1

15 14 13

2 1 1

9

6

10

8

7

5

4

1

3 2

175

MEGAFUSE

Roadside emergencies

197

Fuse/Relay

Location

Fuse Amp

Rating

Power Distribution Box

Description

5 - Not Used

6 10A* Powertrain Control Module

7 30A* 4 Wheel Anti-Lock System

(4WABS) Module

8 15A* Rear Wiper Motor

9 20A* Fuel Pump Relay and RAP

Module

10 15A* Horn Relay

11 15A* Parklamps Relay and Mainlight

Switch

12 30A* Mainlight Switch and

Multifunction Switch

13 15A* Heated Oxygen Sensor, EGR

Vacuum Regulator, EVR Solenoid,

Camshaft Position (CMP) Sensor,

Canister Vent Solenoid

14 30A* Generator/Voltage Regulator

15 - Not Used

1 - Wiper Park Relay

2 - A/C Relay

3 - Wiper High/Low Relay

4 - PCM Power Relay

5 - Fuel Pump Relay

6 - Starter Relay

7 - Horn Relay

8 - Rear Wipe Down Relay

9 - Blower Motor Relay

10 - Rear Wipe Up Relay

1 - Not Used

1 - DRL Diode
2 - Electronic Engine Controls Diode

You must have a problem in the fan circuit, either the fuse, the relay, power to the relay, or the sensor. Easiest place to start is the sensor, on Toyotas of his vintage the sensor is wired so that if it is unplugged the fans will turn on (providing the ignition is switched on) Look to the bottom of the radiator, there will be a sensor with 2 wires. Unplug the sensor and turn the ignition to ON. If the fans go, the sensor is faulty, and is he cause of you fans not turning on when the engine heats up. If the fans remain off, the next thing to check is the fuse. In the fuse box under the bonnet you should find a fuse or fuses labeled fan No. 1 and fan No. 2 (if air conditioning is equipped) NOTE these are sometimes labeled RDS and CDS The labels are on the underside of the fuse box cover. Check the fuse/s by either looking through the top if they are the square type, or pulling them out and looking through the side if they are the blade type. If none of these fuses are blown there is an electrical fault that requires some electrical knowhow to diagnose. The problem could be a blown AM1 or AM2 fuse, which you could also check, these are the battery feeds from the ignition switch to the rest of the car. Usually a blown AM fuse will mean other electrics will not be working either. Another possibilty is a stuck relay, though highly unlikely, as they usually fail to work, meaning the fans will be constantly on. They're named fan No.1 and Fan No. 2 usually You really need to understand how a relay works to check if there is a problem, for instance you can check if the relay coil is being energised by using a test light across the pins in the socket when the relay is removed. You can also check that ignition voltage is being supplied to the contacts of the relay while it is removed. Toyota relays have numbers 1 2 3 4 & 5 for the pins on them. There is usually a small diagram on the relay to tell you which pin is which number, and possibly which pins are the winding and which are the switchable contacts aswell. In general, pins 1 & 2 are the winding, or activator in easier terms, and pins 3,4 & 5 are the switched contacts. Pins 3 &4 are usually common and are disconnected & joined with pin 5 when the relay is energised. NOTE some relays exclude pin 4, and some replace pin 5 with pin 4, leaving only 4 pins in total.
To check the fan circuit with the relays removed, bridge across the sockets where pins 3 & 5, or if it only has 4 pins, pins 3 & 4 and the fan should turn on with the ignition switched on. If not, there is a problem with the ignition circuit.

P0500 and po501 are error codes indicating that no signal is being received from the speed sensor. he speed sensor is located on the output of the transmission and its job is to measure the speed of the output shaft. Check the continuity of the wire from the sensor to the ECU. Check that the connection is securely attached and that the pins are free of dirt and corrosion. To check the function of the speed sensor: If the socket has two pins it is probably a magnetic sensor and one pin is ground and the other should have an output AC voltage in region 0.2 to 2 volts. If the socket has three pins it is probably a hall effect sensor with one pin at reference voltage (5 volts), one pin at ground and the third with a a DC voltage in region of 0.5 to 1.5 volts.
The other code, P0529, indicates that the air circulation fan inside the car is giving intermittent performance, this could be due to warn motor brushes or a loose connector.