4banginRunner

88 xtra cab, originally a 22r/ 5spd non a.c. truck
swapped in 87 4runner harness, 22re and 5spd ( harness is from an a.c
4runner)

Now, fuses are good, relay is good, resistor is good, fan blower is good.
Relay clicks, but I'm not getting power to the blower motor. With a jump lead connected to the blue/ red stripe wire (+ for fan) for the blower motor, I have full functionality of the whole system. Without said jumper, only a click from the relay.
I've tried another heater circuit mini harness with the same results, as well as a different relay, fuses and switch.

What am I missing? Where does the mini harness pull it's power from? Why am I getting power to the relay but nothing to the blower using 2 different harnesses?

Both the 88 truck heater unit, as well as the 87 4runner unit worked prior to the swap.

wyoming9

iTrader: (1)

Poor connection at the 20amp heater fuse maybe loose in the socket

Getting voltage on both sides of the fuse when powered up ??

physical damage to the wires

The relay is good you have tested with a Meter ??

it might pull in but it can still have worn contacts .

Might be loose in the socket or the socket is corroded

where are you getting the 12vdc supply for your jumper wire ??

Any of the connections can be corroded test good with a Meter because the probe makes a good connection when plugged in no connection.

I had one like that fight me for days till I figured it out

4banginRunner

Very low voltage at the fuse without using a jump wire in the circut.
Some how misplaced my multimeter and only have a PowerProbe3
Just replaced every fuse in the truck.

*All with key in the on position*
I apply 12v from the power probe to any of the 3 following wires, I have full functionality of the system;
1 - blue/ red stripe (power for blower)

2- heavy white wire in heater mini harness

3- under hood fuse box at what I assume is the power for white wire in heater harness