ECT failure

This has to be the oddest issue I have ever had with my Tacoma, but I was on I-12 at about 10PM on a Saturday and CEL came on with a code for abnormal voltage to ECT sensor. (Engine Coolant Temperature). I was about 300 yards from an exit so I started slowing down and pulled off. At the stop sign steam started coming from everywhere and engine temp started rising! Luckily there was a gas station right there so I pulled off.

Opened the hood and coolant steam everywhere!

Steam was shooting out of the left side of the water pump buy the alternator and ac compressor?

I have all the parts at my shop, no problem, except I was almost 100 miles from home.

After $700 tow and about 2 hrs labor I had the sensor or water pump changed.

Here is the thing, the water pump I took out seems to be completely fine.

Could the malfunction of the ECT sensor have just built up enough steam to just blow the seals on the water pump????

 

I don’t see how the ECT could have anything to do with the overheating, lose of coolant, or steam.
It just reads temperature. And apparently yours didn’t do that well?

 

Sound fishy

 

ECT sensor code can happen when the coolant runs low enough. the pumps arent an uncommon leak. but the fact you saw steam suggests this leak should be pretty obvious in the form of alot of play in the pump

 

Where exactly did it blow out?
If it blew out by the gasket, then maybe it wasn’t the pump.
Is it possible the coolant was low, the engine overheated, and the gasket was the weakest link?

I can’t say I’ve ever seen a water pump fail in such a manner that it dumped coolant that fast.
But then again, I don’t do this stuff everyday.

 

The coolant was not low. I check fluids regularly. Like I said this probably the oddest thing I have ever had happen. The error code was for sure thrown several minutes before I started seeing steam, then temp started rising. My suspicion, or any case I can think of is possibly the ECT failed and sent a signal to the ECU saying the engine was cold.

I guess it's possible that it was a failure of the water pump gasket, but that would be a big coincidence consider the whole chain of events. I've blown a head gasket and temp started rising and never had an ECT code thrown. It's just odd

 

The ECT does send signals to the ECM
But it has nothing to do with the operation of the cooling system.
The cooling of the system itself is all done by the thermostat.
One could argue that the rate at which the engine warms up is affected by the ECT.
But the operating temperature? No, that’s done by the thermostat, water pump, and radiator.

I still can’t see how the ECT had anything to do with your situation.

 

I can tell you 100% the Coolant Temp Sensor didn't and can't cause an overheat on a 2nd gen as the cooling system is fully mechanical, a Coolant Temp Sensor code could be the result of a severe overheat but not a cause.
You didn't say what code number was set but there are 6 codes related to the Coolant Temp Sensor:

P0115 sets when the temperature reading fluctuates rapidly
P0116 sets when Coolant Temp doesn't change at all for a period of time at varying loads.
P0117 sets if the Coolant Temp Sensor Circuit is shorted or Coolant Temp Exceeds 283F
P0118 sets if the Coolant Temp Sensor Circuit is open or Coolant Temp is less than -39F
P0125 sets if Coolant Temp doesn't rise quickly enough on a very cold start.
P0128 sets if Coolant Temp does not reach at least 167F despite sufficient warmup time.

 

I think I erased the codes, I'll check. The error was something to the effect irregular voltage to ect.

 

It was 0117, I didn't really post this issue to argue, but I kind of agree with the other posters this is just an odd sequence of events that I have never seen in a 1gr-fe. Let's assume the original cause was the water pump gasket failing. With the coolant system full, wouldn't the first symptom be coolant or steam blowing our? Let's face it, it only takes about a cup, if that of coolant to leak before you smell it. (If your a mechanic)

 

I’m not arguing. I think it’s an odd case too.
In your first post you said the code popped up and then the temperature started rising.
P0117 set when the truck get too hot, or the sensor is shorted.
The strange part here is, your truck obviously got hot. But why did the code pop up and THEN the gauge start rising?
Weird???

 

Dood, I totally agree! I've taken 2nd gen Tacoma's apart and rebuilt for over a decade. I've never seen this sequence of events. I did buy, brand new from the factory one of the defective 2nd gen Tacoma's, but I scrapped the crappy Tacoma 1gr-FE and put in a J-VIN made in Japan 1gr-FE from a 2009 J-VIN FJ

 

Wait a second you're telling me my 2014 Tacoma assembled in Texas has a crappy 1GR-FE in it?! Them's fightin' words..

 

I’d start with the thermostat

 

Yeah I dont understand that sentence at all..

 

He is probably talking about an 05-06 with the bad head gaskets.

 

No! Only 1GR-FE made before December 2005!!!

They discovered a flaw in the head gaskets and redesigned them.

So your good bro!

 

EXACTLY!