PDA

View Full Version : St185 radiator fan won't turn on and possible fuel pump relay failing?



lalojamesliz
07-25-2017, 04:00 AM
So like the title says, my radiator fan won't turn on and sometimes after several cranks it won't start but if I take out the fuel pump relay and shake it I hear something loose like a small screw or something. When I put it back, it starts right up.
Any ideas?

lalojamesliz
07-25-2017, 04:02 AM
This blows, I tried to reset the password for my username lalojamesliz and it says my email isn't recognized so I sent a email to a admistrator a couple days ago but since I haven't heard back I just made this username. I don't want to be labeled as a noob again ha ha ha

MrWOT
07-25-2017, 04:30 PM
try turning the key on 5s, off, repeat 3x. attempt start. and/or bypass the relay with a jumper wire see what happens.


can't help with the account though, tried, updating email is not in my bag of tricks, will pass on.

sefiro
07-25-2017, 07:23 PM
Unplug the pigtail from the temp sensor mounted on the bottom of the radiator, the fan should come on. If not, check power at the connector mounted on the fan bracket. If not there, then check fuse and relay.

You can bypass the pump relay with a jumper wire, this will keep the pump running , so only do it in diagnostic processes. If car starts immediately, then relay is likely bad. There should not be anything rattling (spring loaded switch that is overridden by solenoid)

Sent from my XT1053 using Tapatalk

lalojamesliz
07-25-2017, 10:48 PM
try turning the key on 5s, off, repeat 3x. attempt start. and/or bypass the relay with a jumper wire see what happens.


can't help with the account though, tried, updating email is not in my bag of tricks, will pass on.

This is for the pump right? I opened up the relay and found a small piece of solder rolling around on the inside. I took it out and it starts right up every time now. I didn't see anything not connected. I'm going to guess that small piece was just getting in the way of the connection :)
I only have the fan problem now :(

lalojamesliz
07-25-2017, 11:05 PM
Unplug the pigtail from the temp sensor mounted on the bottom of the radiator, the fan should come on. If not, check power at the connector mounted on the fan bracket. If not there, then check fuse and relay.

You can bypass the pump relay with a jumper wire, this will keep the pump running , so only do it in diagnostic processes. If car starts immediately, then relay is likely bad. There should not be anything rattling (spring loaded switch that is overridden by solenoid)

Sent from my XT1053 using Tapatalk

I didn't even check if I had power at the plug with the temp sensor unplugged. I DO! I think the wires are just crossed. I'm going to switch the wires and see what happens right now

sefiro
07-25-2017, 11:33 PM
The computer sends a control signal to the the temp sensor, the sensor, via thermos resistor, changes the voltage that goes back to the computer. Once the voltage crosses a threshold, the computer sends a switch signal to the relay which switches on the line for the fan. For most of this era Toyota's, the disconnected pigtail creates a maximum resistance reading which trips the threshold so the fan should turn on

Sent from my XT1053 using Tapatalk

lalojamesliz
07-25-2017, 11:36 PM
The computer sends a control signal to the the temp sensor, the sensor, via thermos resistor, changes the voltage that goes back to the computer. Once the voltage crosses a threshold, the computer sends a switch signal to the relay which switches on the line for the fan. For most of this era Toyota's, the disconnected pigtail creates a maximum resistance reading which trips the threshold so the fan should turn on

Sent from my XT1053 using Tapatalk

Nothing happens, if I unplug the sensor I see voltage at the plug from the harness but nothing happens with the fan? With the car on and off.
Earlier I ran the fan off a battery to verify it works and it did. I don't know what's happening....

lalojamesliz
07-26-2017, 12:08 AM
The plug from the harness side has voltage but not enough current to event trigger a relay. Wth!

sefiro
07-26-2017, 12:13 AM
The computer does not have wiring and transistors large enough to handle current demands of electrical motors and non led lights, so they used relays that would take low current signals and use them via solenoid to switch on the larger wires that could handle the current - relay.

You can pull the relay and check if 12v exists on two of the legs - one being the signal from the computer and other being the main line back to the fuse box/battery.

Sent from my XT1053 using Tapatalk

lalojamesliz
07-26-2017, 01:56 AM
The computer does not have wiring and transistors large enough to handle current demands of electrical motors and non led lights, so they used relays that would take low current signals and use them via solenoid to switch on the larger wires that could handle the current - relay.

You can pull the relay and check if 12v exists on two of the legs - one being the signal from the computer and other being the main line back to the fuse box/battery.

Sent from my XT1053 using Tapatalk
I know what you mean, I was trying to see if I could trigger a relay I wanted to install with the plug for the fan but it didn't put out enough power to trigger the relay.
Screw this, I actually have a ron francis ar88 adjustable temp fan relay kit coming tomorrow for the mustang I'm building and since I won't be needing it for my mustang anytime soon I'll just use it on my all-trac for now

Murgatroy
07-26-2017, 02:16 AM
I updated your original account to your new email ending in aol.com. You should be able to recover now.

lalojamesliz1
07-26-2017, 04:26 PM
I updated your original account to your new email ending in aol.com. You should be able to recover now.

Thank you :)

lalojamesliz
07-26-2017, 05:15 PM
I updated your original account to your new email ending in aol.com. You should be able to recover now.


Sweet! Thanks Murgatroy! Now I'm back RIP lalojamesliz1 ha ha ha

ChrisD
07-26-2017, 07:42 PM
Can we give him the noob label anyway??

My money is on a bad fan relay or water temp switch.

http://www.celicatech.com/bgbonline/90alltrac/CO/CO-9.jpg

lalojamesliz
07-27-2017, 03:34 PM
Can we give him the noob label anyway??

My money is on a bad fan relay or water temp switch.

http://www.celicatech.com/bgbonline/90alltrac/CO/CO-9.jpg

I just replaced the relay but not the switch....... If the switch (sensor right?) Was bad, wouldn't my temp gauge not read properly?
The temp gauge looks good when I drive it.

lalojamesliz
07-27-2017, 04:01 PM
For many things I do need a noob lable.... exhibit A:

It says to use a ammeter on the harness plug right?
That's the 15a fused setting on my multimeter right? (Lol)
Would that cause a short?
I thought you use this when you break a positive connection and use this setting and the leads to complete the connection to the power source.
Explain what to do pretty please :)

sefiro
07-27-2017, 08:03 PM
The temp change uses a different water temp sensor , located on the water housing mounted to the head.

Amp (am) meter is hooked up in series with the wiring , ie, disconnect the battery cable, and use the ammeter to connect the cable to the battery (note, if you do this with a low end ammeter and start the car you will fry it(cars running 60-100 amps if everything on). We typically use the am meter in this mode to find shorts , hook it up, car off, take a reading, start pulling fuses to see what causes the reading to drop.

Since your fan is not running, it's not using power and thus won't register on the am meter. Use the voltage reading on the meter , it will tell if there is a difference in voltages (like positive/negative terminals on a battery).

To find suspect switch, relay, wire problem , you find a known good voltage higher up the circuit (closer to the battery). Then work down the circuit placing the leads on both sides of the item. If item is working, then there would be 0 voltage, if broken, the 12v difference. Typically, we place the ground leaf on the battery ground and them work the circuit with the positive lead.

Sent from my XT1053 using Tapatalk

lalojamesliz
07-29-2017, 07:10 PM
I ended up putting a switch and relay to the fan for now so I can start driving it.

lalojamesliz
08-17-2017, 06:57 PM
Update on my fuel pump issue, it was still giving me problems starting. I don't remember why but I took off the relay and looked and the blades on the bottom and found corrosion on one of the blades.
It also looked like it had a bad connection. I cleaned off the corrosion and tightened the connectors for the blades a little so they have a tighter connection and it started up no problem after that.
Now it's just sitting waiting for my gen3 electronics to arrive to swap over since I just passed smog and it's good for a little over 2 years :)