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This is an interesting thread, and I wonder what happened to the OP's car: I'm having the exact same problem with a 2000 Honda Insight: Start it up and it will overheat within 5 minutes. One burp of pressure in the water system on start-up, then no bubbles, then bubbles as the coolant boils in the jacket. Top hose hot, bottom cool, thermostat tested and works perfectly (and the replacement works as well)
What would be the symptom of a bad pump? I can see the impeller blades, and jamming them with a screwdriver prevents the pump pulley from turning. Compression is 120/90/120 stone cold and 200/180/200 with 5ml of oil injected into each cylinder to rule out ring wear (yes it's really worn. It's a junk car)
When you supply 12V directly to each of them via a small 12V battery, do they each come on at full (high) speed?
Supplied 12V (fused) by bridging Fan Power terminals of the final stage harness to Fan grounds of the the same harness.
They turn on strong but have no reference benchmark to determine whether it's indeed full high speed or half speed. Speed is same relative fan to fan.
Assume they are original to the car, fan shroud is standard and no signs of alterations. Both fan operation failed at the same time.
Has any one heard of fan failure due to insufficient loads detected by either the controller/final stage?
Am wondering whether there are tests to rule out the controller or the final stage. Looks like an oscilloscope is required for PWM sense signals. What kind of signal should "Ux Final Power to Final Stage" be?
removing the connector from the switch at the front of the radiator, then turning on the key to run will trigger the fans to run.
Touching the two wires together at the top of the intake manifold sensor will cause the fans to run without regard to the key being on.
Report what you see please
If only the drivers fan comes on when touching the two wires at the top of the intake manifold sensor, and the key has to be on-what does this point to?
If only the drivers fan comes on when touching the two wires at the top of the intake manifold sensor, and the key has to be on-what does this point to?
A dead fan. You can confirm by supplying 12V and a ground to the fan that’s not running. Replace in pairs, about $175 each.
on my 89 one fan was running on high all the time-
I bought a used final stage controller.
I seemed to be working and turning on the fan when needed.
The other day with the new/used controller I had no fans with a high temp warning.
I cleaned all grounds, and used deoxit wherever I could.
The unit began working again.
Today I got another high temp warning with no fans.
I jumped the temp sensor on top of the manifold and only got the drivers fan going.
Now when I put back the original final stage controller I get both fans when jumped (key to on position)
Now I am wondering if my original controller has an intermittent failure, and/or if the new/used controller is also bad.
Last edited by PC-85-928S; 06-04-2020 at 08:13 AM.
When I first got the car the cooling flaps were contiguously opening and closing-
I pulled the relay not the fuses-
does that COOLONG AIR FLAP RELAY (944.615.119.00) in the XVIII position need to be in for proper fan operation?
When I first got the car the cooling flaps were contiguously opening and closing-
I pulled the relay not the fuses-
does that COOLONG AIR FLAP RELAY (944.615.119.00) in the XVIII position need to be in for proper fan operation?
No, leave it out. Those flaps are a PITA.
The fans do age and start doing odd things like running very slowly or working sometimes and sometimes not before they stop working at all. Once you reach the not running stage you know they are completely done.
The very easiest and simplest thing you can do it just supply 12V and a ground to each fan, they should each come on at high speed and stay on high.
11-19-2019, 08:53 AM
