[Clmartin0721]

Hello all,

I have a 2007 corolla with 160K miles, strong runner with no problems to date.

On the way home last week the temp gauge started swinging erratically from normal to cold, and the ac system wouldnt run for a short period of time. There was also a bit of a high speed engine surge which happened 3 times within an hour of drive time.

replaced the fuel pump and relay (I realize that this was probably unnecessary, but was more of a preventative step) and the temp sender.

Problems now are as follows;

1. Will not start when cold without starting fluid
2. Fan is running at high speed even when engine is stone cold
3. Once car starts and runs for 5 minutes it runs perfectly and will restart normally while warm
4. the colder the car gets, the harder it is to start
5. P0118 code is persistent even after clearing the system
6. tested two known good temp senders with no change
7. the connector and wiring look perfect
8. AC is running fine
9. Water pump and thermostat are 1 year old with no signs of issues

Was going to check for 5v at the connector, and then jumper the connector to see if max temp is registered at the ecu ( with obd scanner)

I am thinking the only possible culprits are an open circuit or the ECU, but I wanted to throw this out to see if I am missing anything. I am willing to get the two day Toyota tech access if needed for diagnosis.

Any ideas? Am I missing something? I really appreciate any help anyone could provide, as I need to get this fixed.

Thanks for your time

Craig

 

[John Anthony]

replaced the fuel pump and relay (I realize that this was probably unnecessary, but was more of a preventative step) and the temp sender.

The fuel pump on the Gen 9 Corolla rarely goes bad. It's well known to be a very durable item on this application. 352K miles on my original fuel pump. P0118 is often the temperature sensor (you've already replaced it), but it could also be the wiring to the temp sensor. It could also be very bad, dirty, or rusty radiator coolant.

1. Will not start when cold without starting fluid
2. Fan is running at high speed even when engine is stone cold
3. Once car starts and runs for 5 minutes it runs perfectly and will restart normally while warm
4. the colder the car gets, the harder it is to start

Your car thinks the engine is always hot, even when it isn't, which may be why it's hard to start when it's cold and why the fans are on. A faulty A/C pressure switch could cause the fans to run at high speed even if the engine is cold.

7. the connector and wiring look perfect

I had no signal going to my front O2 sensor. The wiring was undisturbed, but I eventually found out that a shielded wire had the outermost wire penetrate and short out the signal wire even though it looked undisturbed. Does the coolant temp sensor have a wire that is shielded or a wire that eventually turns into a shielded wire downstream of it?

Was going to check for 5v at the connector, and then jumper the connector to see if max temp is registered at the ecu ( with obd scanner)

Yes, I think that's a good idea to check for 5 volts at the connecter, and jumper the connector to see if max temp is registered at the ecu as displayed on a scanner.

 

[hardtopte72]

If you send me a PM, I can get you the repair documents for the code.

Long story short, your code is specifically for an open circuit in the ECT circuit. This can only be caused by a cut wire, and sensor, or bad ECM. Since you supposedly ruled out the sensor (I would highly recommend ensuring you have a Toyota sensor installed), you have to check wiring and the ECM.

 

[John Anthony]

Since you supposedly ruled out the sensor (I would highly recommend ensuring you have a Toyota sensor installed), you have to check wiring and the ECM.

Yep, I thought I had asked what brand of sensor he used, but I guess that was another thread. I'm thinking the wire is compromised somewhere.

 

[John Anthony]

The quote and multi quote feature isn't working for some reason. My last two posts had quotes before my responses, but the quotes are not showing up. Anybody else having this issue?