Looking for the cooling system wiring diagram or something that includes the complete circuit for the radiator fan, coolant temp sensor, relay, etc. This is for my '88 hf with a b20z2 swap.

I can't find a for sure diagram in the Haynes manual for this and would prefer a factory diagram if possible.

Here's a rundown of whats going on. Found the plug for the fan and plugged it back in. The car warms up just fine and never registers to be running hot. The relay can be removed and you can jump the harness pins to make the fan come on, but it will not under normal conditions with the relay plugged in. Made sure the fuse is good under the dash. Tried to test the relay and even opened it up to ensure it wasn't burnt up. Swapped the relay from the A/c and tested it with the car running and still not kicking the fan on when the engine gets hot.

Any other suggestions? and yes, this is why I want to get a for sure diagram of this circuit so I can properly test this stuff out.

Also, how would the instrument cluster register the engine getting warm when the coolant temp sensor on the thermostat neck was unplugged, or is this even the coolant temp sensor?

--Justin


Modified by racin_fool at 4:51 PM 3/11/2006

 

cooling system has three sensors:

one on end of head below distributor with one wire connector with yellow/green wire - this is the temp gauge sending unit

one on end of head below distributor with two wire connector with red/white and green/white wires - this is temp sensor for ECU

OBD0 engines - one on back of block next to oil filter with two wire connector (big black rubber boot) - yellow/green and black wires - this is cooling fan switch

OBD1 engines - one on thermostat housing with two wire connector - extend yellow/green and black wires from OBD0 location to the thermostat housing and install different connector - this is cooling fan switch

 

Alright, I found the two wires and extended them to the thermostat housing sensor for the cooling fan switch. This is on an OBD0 system and harness with a b20z2 swap using a modified stock harness with a 90 LS ecu. I tried warming up the car and the fan still would not come on unless I unplugged it from the sensor at the thermostat neck and jumpered the pins.

1st question. Do the 2 different sensors (the one on the back of the block and the one on the thermostat housing) have the same resistance values?

2nd question. Would the b20 block have a port to use at the back of the block for the stock sensor?

3rd question. Would it be possible to use the sensor at the thermostat housing instead of the one at the back of the block since it is no longer located there?

Last question. Does anyone have the specs for both sensors as to what the resistance values are supposed to be at specific temperatures?

Thanks again guys..

 

does anyone have even part of the answers I am looking for?