Exhaust Manifold temperature sensor

[desmocruiser]

It is a sensor pointing toward the exhaust manifold mounted on the section of metal PCV hose that bolts into the intake manifold.

Is this necessary to have on a desmog rig?

Sorry no pics at the moment.

 

[Miloslavich]

What that does is regulate the Carb fan after you turn the rig off.

if you want the fan to work as it is supposed to, keep the sensor.

others have simply wired their fans to run for 30 mins after turning their engines off.

 

[GLTHFJ60]

others have simply wired their fans to run for 30 mins after turning their engines off.

...by taking the wire that goes to the sensor and simply grounding it to the body. Piece of cake.

 

[LAMBCRUSHER]

so what, the chip has an off delay built into it?

 

[Spike Strip]

so what, the chip has an off delay built into it?

There's a timer relay under the pass side kick panel.

O.P. -- Chances are the temp sensor at the exh manifold is no longer functional, or the wire to it has been melted. Is your carb fan (large blower on driver's fender at firewall) coming on ? If yes, leave everything alone. If no, take the single wire that would go to the thermosensor and ground it to any bolt on the fender. Your carb fan should now run for 20-30 mins after you turn the key off, and anytime you cycle the ignition key.

 

[Output Shaft]

Here is the cave-man, get-it-done-before-Monday way...
Wire the fan directly through this. There's a good mounting spot next to the hood latch puller. Gotta remember to twist it on when you turn off the engine though. The original OEM automatic manifold sensor is the kitty's milk, but this is better than no fan at all.. that's for sure.

Woods 59714 30-Minute Spring Wound Timer - White

 

[GLTHFJ60]

Here is the cave-man, get-it-done-before-Monday way...
Wire the fan directly through this. There's a good mounting spot next to the hood latch puller. Gotta remember to twist it on when you turn off the engine though. The original OEM automatic manifold sensor is the kitty's milk, but this is better than no fan at all.. that's for sure.

Woods 59714 30-Minute Spring Wound Timer - White

Don't do that. Just wire the sensor wire to a ground and the carb fan will run for 30 minutes (IIRC) every time you shut off.

 

[GLTHFJ60]

Here is the cave-man, get-it-done-before-Monday way...
Wire the fan directly through this. There's a good mounting spot next to the hood latch puller. Gotta remember to twist it on when you turn off the engine though. The original OEM automatic manifold sensor is the kitty's milk, but this is better than no fan at all.. that's for sure.

Woods 59714 30-Minute Spring Wound Timer - White

Don't do that. Just wire the sensor wire to a ground and the carb fan will run for 30 minutes (IIRC) every time you shut off.

 

[Cruiserdrew]

The fan is highly useful even in a desmog. It keeps the carb from vapor locking and works great for this. As was said, you can either ground it, or wire it like stock through the temp sensor.

 

[Output Shaft]

Don't do that. Just wire the sensor wire to a ground and the carb fan will run for 30 minutes (IIRC) every time you shut off.

Yes grounding the temp wire is the best solution… if one's electrical system is not all messed up.. like mine.
Perhaps this thread has opened up a new can of worms?
My temp sensor/Carb fan went to sheet, along with:
Headlights, Cabin fan, Dome light, Parking brake light, Windshield washer pump, Instrument indicator lights wrong (turn signal flashes the hazard indicator) & a few other things I rewired… always before Monday & tried to forget. You should see my battery accessory terminal.. there are at least 8 new wire ring connections to it with dangling fuses. Wing nut barely fits the stack…it's embarrassing and does not do the Land Cruiser proud.

I suspect everything points to a chafed wiring harness.. If so, is there a likely spot? Some have said on passenger side where wiring harness goes through firewall….. That monster is all bundled up and it looks like it would require a full car teardown to examine it properly. I couldn't see anything obvious & I gave up... not wanting to make things worse. No way to get it done before Monday..

But now I have the time to find the wound.. and fix it. Any ideas?

This Fj60 has traveled many thousands of miles vibrating itself to death on Mexican dirt roads.. and the electrical mayhem started after a long ass dirt road trip several years ago…. hmm.

 

[LAMBCRUSHER]

12 volt programmable relay run about 60-100 bux; has 4+ inputs to operate 4+ output channels, or an internal sequencing program and no inputs needed- you could even do a temp sensor to trigger it ala oem. I have given it some thought...a series of relays and a timer would cost more.....

 

[RIBob]

What is the resistance of the manifold sensor when engine is cold and what resistance level signals the relay to turn the fan on?

 

[Spike Strip]

What is the resistance of the manifold sensor when engine is cold and what resistance level signals the relay to turn the fan on?

Far as I know there are no resistance values. It's just an on/off thermal switch at a set temperature.

There's a thread where someone used a SPAL switch

185 F Thermostatic Fan Switch - SPAL 185-TS

185 F Thermostatic Fan Switch - SPAL 185-TS

www.fcpeuro.com