2000 WRX post engine re-build, no start and thermo fan/temp issue

jezzwon
Learner Driver
Posts: 5
Joined: Mon Apr 24, 2017 9:16 am

2000 WRX post engine re-build, no start and thermo fan/temp issue

Postby jezzwon » Thu Oct 19, 2017 1:27 pm

Hey all,

I've done a lot of searching and can't seem to troubleshoot my issue(s) - I'm hoping the good people of the forums can shed some insight!
Quick backstory - ej205 motor with quite a lot of bolt ons, just pulled it and the tranny out to refresh the motor, new oil/water pumps, TB etc. etc. Been lucky enough to do it at my mates workshop with hoists and lots of tool options.

Everything has gone back in but unable to start.
With the ignition turned OFF, ie key out, the car throws a CEL, both thermo fans kick in full bore and the temp gauge goes to max! Obviously not an ideal static state. I tried unplugging the two sensors under the alternator (three pin is def coolant sensor (for ECU?), is the other the temp gauge sensor or a separate pressure sensor of some sort?)
My suspicion is that i've somehow damaged the ageing engine harness putting it back in and the sensor wire is grounding out - or will a failed coolant sensor also give these symptoms? The car currently has water in it, not coolant until we work out this thermo/temp issue.

Some photos: https://imgur.com/a/MaSye

The bloody brant is also interfering as I haven't heard the fuel pump kick in, nor been able to enter my PIN and fire up the ECU to connect to my mates scan tool.
I've tried the # + 0 reset but it didnt work, so I think I might have to get an auto elecy to pull it out and install a different system to try and get this thing running again!!
The motor is turning over no worries, just no ECU power or fuel pressure at the moment.

Any help is appreciated guys, thanks

EDIT - nothing is hot the engine hasn't started so no reason for the temp gauge to read high other than a system error

mv75
WRX STi Driver
Posts: 841
Joined: Sat Dec 27, 2014 9:26 pm
Location: Brisbane Northside.

Re: 2000 WRX post engine re-build, no start and thermo fan/temp issue

Postby mv75 » Thu Oct 19, 2017 3:19 pm

Sounds like you have the diagnostic plugs plugged together. But the key is out. Strange.

The single pin sensor infront of the engine stamp is your oil pressure sensor.

Pull the main harness plugs behind the battery, the two large plugs and check the pins.

Definitely piss off that brant.

jezzwon
Learner Driver
Posts: 5
Joined: Mon Apr 24, 2017 9:16 am

Re: 2000 WRX post engine re-build, no start and thermo fan/temp issue

Postby jezzwon » Thu Oct 19, 2017 4:05 pm

mv75 wrote:Sounds like you have the diagnostic plugs plugged together. But the key is out. Strange.

The single pin sensor infront of the engine stamp is your oil pressure sensor.

Pull the main harness plugs behind the battery, the two large plugs and check the pins.

Definitely piss off that brant.


Not the diagnostics plugs, just this morning i tried plugging/unplugging these.

I did remove the two main loom plugs behind the battery - in general the engine loom is looking pretty sad from years of heat. Is there only the one coolant temp sensor on these models as far as you know?

mv75
WRX STi Driver
Posts: 841
Joined: Sat Dec 27, 2014 9:26 pm
Location: Brisbane Northside.

Re: 2000 WRX post engine re-build, no start and thermo fan/temp issue

Postby mv75 » Thu Oct 19, 2017 4:45 pm

Yes, should be just the one.

If you wanted to remove that loom off the manifold and refresh/check it, you can get the suitable sized plastic ribbed casings and a bunch of electrical tape from jaycar.

jezzwon
Learner Driver
Posts: 5
Joined: Mon Apr 24, 2017 9:16 am

Re: 2000 WRX post engine re-build, no start and thermo fan/temp issue

Postby jezzwon » Mon Nov 13, 2017 5:54 pm

Resolved.

I'm an idiot and had for some reason had connected the earth wire of the engine loom to the active on the starter motor.
Hence, thermo fans had power supply when key was off and the sensors were going nuts.
Oddly, the ECU wouldn't power up when connected in this configuration.
As soon as the wire was put back to ground the car fired up.

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