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Swap Electrical Testing

638 views 14 replies 3 participants last post by  camaroz1985 
#1 ·
Would it work/be worth it to put a battery in the car and test the electrical stuff while I'm waiting on my engine? I just want to try to get as many bugs worked out as I can before the engine gets here.
 
#2 ·
yup. things to check:

1. lights
2.cluster
-check for check engine light, should come on with the key on. If it doesn't...something isnt right
3. ebrake light

etc etc. just make sure you be VERY careful when you connect the battery. Touch the terminal and watch everything for smoke or a burning smell. Dont want to connect it then realize something is shorted and melt your entire harness.
 
#4 ·
psh, i dont have a motor....just grounded all of hte wires to the chassis...no biggy.

Yes, you cant test much, but you can test that there aren't any major problems like shorts. My car is wired (by me) (awaiting my built engine) and i put the battery in and tested the ECU, fuel pump, lights etc.
 
#12 ·
Ok so I got it all back in and threw a battery in there. I get most of the stuff functioning as normal. There are a few things that I have noticed that are odd.

First, the fuel pump doesn't prime. I get 11.5V at the FPC and 10.4V coming from the FPC. I also get 10.4V at the fuel pump plug, so I'm guessing that the "brand new" pump that came with my swap is not any good. Is there really a difference between the 98 RS pump and the 07 WRX pump?

Also the blower works only on high speed. I know this is usually a symptom of a bad blower motor resistor, but it worked fine when I started things. Could banging it around while taking out the blower box have messed it up? What are the normal readings for resistance?

Also is there any way to check if the immobilizer is functioning properly? There is signal sent to the fuel pump, but is that proff the immobilizer is working?

Any help would be appreciated guys, thanks.
 
#14 ·
It's easy to check. Pull the resistor out and see if there is a piece of metal making noise. Kind of like a dead light blub. You can actually fix it. If you cut it open you can solder the part that came off back on. You are getting different voltage at the FPC because it's doing it's job. It's modulating the ground so that your fuel pump does less work at idle and when you hit the gas it will dump more fuel.

As far as the immoblilizer you could hook up an LED to the security light wire from it. But it will turn on the fuel pump when you put the key on, however the pump will stop a few seconds later.
 
#15 ·
Ok pulled fuel pump back out and connected directly to a battery, it runs. Put it back in the assembly and did some more testing, still doesn't work. Rechecked all the connections they are all fine. When I bypass the FPC it runs. I notice that when the FPC is connected it gets a voltage, but no amps. I'm hoping this is one of those strange things you talked about Keener.

Oh and the resistor was bad. A little ball of solder had fallen off. Resolder it, and its good as new. Thanks a lot!!
 
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