seoul2k

So after doing a valve adjustment I put the valve cover back on and as soon as i started the car up it died right away. Had no idea what was going on so I tried starting it again, but it soon died right after. So I plugged my snapon OBDII scanner in and saw that it was P0118.

P0118 - Engine Coolant Temperature Circuit.

Followed my Honda manual and did the test by checking the readings of the scanner and I was getting -40 which meant that it wasn't getting any connection. So it said to unplug the sensor and put a jumper wire inbetween, which I did and it ends up reading -40 for ECT. So the next step was to check it at the ECM harness and i put a jumper wire in between the two spots that needed jumping and it didn't do anything. Still the same thing -40 readings for the ECT. Then they said swap out the ECU for a known good one and It came out the same. I also ordered a new 2003 ecu.... So basically it tells me to fix the broken connection.

I was trying to read the Honda Manual for the wiring diagram, but it wasn't really working out to well. Now if i cut the 2 wires at the ECM and make a new connection for the ECT sensor would that work? As far as i know it says that the one wire is for the ECT, but the other wire is for a sensor ground. It doesnt specify what sensors it is the ground for... I want to try this before having to buy a new wiring harness...

I should have figured it was a wire issue because after putting the valve cover back on it started happening.

Wiring help would be much appreciated, as far as electrical stuff i'm clueless.

T-Smac

Are you sure your scanner was updating quick enough. If you are properly jumping the connection at the ECM, and your reading still reads -40, you have a bad ECM or your scanner is inoperative / slow to update. With it jumped your reading should be close to 300. If reads 300 jumped at the ecm but -40 jumped at the ECT connector, you have an open in the wiring.

I would try jumping it again at the ECM and make sure your jumper wire (or whatever you are using to jump the terminals) is making good contact with the terminals of the ecm harness.

seoul2k

I found out that my problem was the wire harness. I actually ordered another ECM, but that wasn't the issue at all. I removed the whole harness and used a multimeter to find the break in the harness. The green white wire for the ECM was cut near the ECT sensor. I guess when i did a valve adjustment the wire was very brittle and just broke. when re-installing the valve cover. I replaced a lot of the wires just in case and re-wrapped everything. I'm just trying to reinstall the harness now.

seoul2k

runs like a dream now