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Old 03-10-2018, 08:23 PM   #1
awboothby
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Default 2006 STI - Electrical Hunt

Hi All,

I just picked up a 2006 STI from a guy who didn't want to take the time or money to figure out whatever problems it may be having.

Here's the story I got from the guy, 4 months ago:
1. Driving car down highway around 60-65 mph steady
2. ALL electrical power goes out and engine quits
3. Towed back to his house, battery is fully charged when checked.
4. He doesn't do much investigating and then later decides to sell it.
5. I buy it 4 months later


My findings so far:
1. Battery is partly discharged from sitting for a while ~6V.
2. Take out battery, charge it back to full
3. Battery in car and connected, fully charged.

Here are the current symptoms after looking through some of the top-level basics:
- When key is inserted, I hear the normal dinging that you would expect when inserting the key (which means power is at least getting to whatever controls the dinging).
- None of the other electrical systems seem to turn on at any time, no lights, no dash, no radio. Regardless of key position. No relay clicks are audible.
- Checked all fuses in engine bay.
- Checks IGN, ABS, Radio fuses in the kick panel (I would like to check ECU fuse but I am not sure which one it actually is). Tried some other fuses and all are good.
- Have not checked any specific relays yet.
- Keyless entry does not respond.


- My first thought is that the ECU might be dead or the keyless entry or security is immobilizing the vehicle (but that would not necissarily correspond to the fact that the car died while being driven by the last owner). Maybe I am wrong though since I am not very familiar with the symptoms of the security system.

- Second thought was that the alternator was bad and car just died on him once the battery finally dropped out. However, fully charged battery does not change symptoms.


Does anyone have any thoughts on why the car would beep/ding normally when the key is inserted, but not respond at all to rotating or engaging the key?


Thanks a bunch!

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Old 03-11-2018, 03:57 AM   #2
CosmoTheCat
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Electrical portion of the ignition switch died, or wiring thereof. Dead main relay. Ground went away somewhere. One of the main SBFs or fusable links is blown. Connector unplugged somewhere.

This sounds like a fun one to diagnose.
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Old 03-11-2018, 09:17 AM   #3
Charlie-III
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How are you checking fuses? Metering them is the better way, too many times they get "looked at" but they are cleared.

Are you metering the battery voltage when you turn the key on? If so, does it stay up around 12.5 volts?
From there, it's just searching through circuits to see where the issue is.
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Old 03-12-2018, 02:35 AM   #4
awboothby
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Quote:
Originally Posted by CosmoTheCat View Post
Electrical portion of the ignition switch died, or wiring thereof. Dead main relay. Ground went away somewhere. One of the main SBFs or fusable links is blown. Connector unplugged somewhere.

This sounds like a fun one to diagnose.
Yeah, it's going to be interesting to say the least. Unfortunately I'm not able to get it up on my lift right now because of another project, so I'm having to do most of the work in the parking lot for now.

I'll definitely start taking a look at the ignition switch and relays, as well as the grounding. I checked out all the SBF's (especially #5 which seemed like the most likely candidate at first based on the schematics), but they are all good. So, on to the relays, wiring, and modules I think.

Quote:
Originally Posted by Charlie-III View Post
How are you checking fuses? Metering them is the better way, too many times they get "looked at" but they are cleared.

Are you metering the battery voltage when you turn the key on? If so, does it stay up around 12.5 volts?
From there, it's just searching through circuits to see where the issue is.
Yep, I ohmed them out with a multimeter.
Thanks for the idea on the battery. I did not check if the battery voltage was being affected by the key position. Today I measured it and watched the voltage as I moved the key into each position, but the voltage did not even move by 1 mV. I'm assuming that means no relays are switching and changing the draw on the battery.



Note: One thing I did notice today is while probing fuse #11 (E/G IGN) -> without the key in the car, the voltage flatlines at 0. When I insert the key the voltage pulsates at a 1-2 second interval from 0 to about 40-50 mV continuously. This is the case with the key in any position.

My first thought with seeing voltage behave this way would be some sort of hard or soft short down the line somewhere... However, all of the fuses seems to remain closed.


Thanks!
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Old 03-14-2018, 08:58 PM   #5
Cougar4
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What we have here is really called....a bad or faulty connection to power, not a short of any kind or sort.

You say fuse 11 has no power to it with the key in the RUN position. This means that power may not be getting to the ignition switch or the switch itself s bad. Power gets to the switch via a white wire that is tied to fuse SBF-4 in the panel under the hood. If that fuse is okay and has power to it then check the output connector (F38, a single white wire connector) to the fuse panel and make sure that power is getting to that point. If that is okay then check the connection at the switch. If you have no power there then suspect connector F46 a two pin connector. The connector is located under the dash, in the corner on the driver side.

Last edited by Cougar4; 03-14-2018 at 09:10 PM.
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Old 03-19-2018, 10:17 PM   #6
awboothby
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Good new / Bad News.

Good News:
Thanks for all the input on this. Turns out, the main 120A SBF was actually blown, but didn't show up as blown with the multimeter set to continuity between the leads while installed in the car.

I noticed this when probing voltage on some of the lines that should come directly downstream of SBF1, and the voltage was at 12V when nothing is attempting to draw current. Once I put in the key and try to turn it, the voltage dropped to 0.6V or less.

Not sure anyone has seen this before, but as an EE, by guess is that the SBF did not blow out to 100% open, and has just enough material left to cause a high resistance path for the main circuit. It got stuck in a situation where the voltage dropped off faster than any of the electronics could come online to blow the fuse the rest of the way out. (The 'key inserted' chime and the horn are not behind SBF1).

Replaced SBF1 and all electrics are back online.


Bad News:
Once electrics were back on, I quickly discovered the engine is seized. Looks like my road to getting back in a working STI is a lot longer than initially anticipated.


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Old 03-20-2018, 12:40 AM   #7
Charlie-III
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Well, glad you got the electric fixed.

What do you mean the engine is seized? How did you determine this?have you pulled the radiator fans and used a ratchet and 22mm socket to crank the engine over at the crank bolt (turning CW only)?
If it won't spin, pull the spark plugs and try again.
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Old 03-20-2018, 04:03 AM   #8
CosmoTheCat
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"driving down the freeway and the engine quits"

Yeah.

I bet it did....
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Old 03-21-2018, 01:47 AM   #9
awboothby
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Quote:
Originally Posted by Charlie-III View Post
Well, glad you got the electric fixed.

What do you mean the engine is seized? How did you determine this?have you pulled the radiator fans and used a ratchet and 22mm socket to crank the engine over at the crank bolt (turning CW only)?
If it won't spin, pull the spark plugs and try again.
Yes, tried turn it with a socket to check once I had the suspicion. It wont budge at the moment. The started sounded like it was trying but there was no visible movement on the pulley.

I've already scheduled myself in for an engine build at PIA up here in nearby Tacoma for later this year. But I will continue dinking with it until then to see if I can get a clearer picture of what's going on.

Does anyone have any experience with penetrating oil (MMO or anything similar)? I'll take a look inside first to check for any actual broken parts.

(Note: I'll probably stop this thread here and reference it in a new thread in the 2.5L EJ sub-forum)

Quote:
Originally Posted by CosmoTheCat View Post
"driving down the freeway and the engine quits"

Yeah.

I bet it did....
LOL. Yep...
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Old 03-21-2018, 09:09 AM   #10
Charlie-III
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Silver Sleeper BK, 5MT

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You ask about penetrating oil, you thinking the rings rusted to the cylinder wall?
If so, I HIGHLY doubt it.

Did you remove spark plugs and try with the ratchet again? Long stretch could be hydrolocked, removing the plugs lets you spin it by hand since water can come out the plug hole. If hydrolocked, think bearings, connecting rods, etc.
If no change, then pull timing covers and check the belt.
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