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dash wiring harness problems


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16 replies to this topic

#1 Scotty1419

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Posted 31 August 2011 - 03:19 PM

Well i called my mechanic who did the 2.2 swap for me and he said he will do another engine swap.. but he said there is a possibility that that may not even fix my miss fire and that it very well could be a electrical wiring harness problem in the dash. My question to you guys is, how would i go about checking electrical things under the dash and what should i be looking for? burnt wires or?? And also what electrical wires would cause a missfire if they werent working right? I am assuming ignitor, maf, cam and crank sensor, knock sensor wires? Thanks

Edited by Scotty1419, 31 August 2011 - 05:56 PM.


#2 grossgary

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Posted 31 August 2011 - 03:58 PM

why did he say it's a dash wiring problem? that's highly unlikely. that's kind of like saying a tooth ache is stage 3 cancer....

i'd start another thread to determine what is wrong with your engine first, then move on to catastrophic things once we've narrowed it down better.

if you end up needing to look into the wiring:

i would rather do the engine swap, it's easier. so switch jobs - you do the engine swap and have a mechanic do the dash pull and wiring trace!

#3 Scotty1419

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Posted 31 August 2011 - 05:45 PM

well that's just the thing.. we don't think anything is wrong with my engine.. we've replaced just about everything you can for a misfire and compression was spot on.. The diagnosis is that my car is definitely running rich and fouling up plugs.

I checked the wiring leading into my ecu and there was definetly work done there.. i counted about 8 wraps of electrical tape on different combinations of wires. some of the electrical tape was gray(factory?) and the rest was black electrical tape. now i know for a fact ive never been under there splicing together wires so it wasnt me.

My question is would a 98 legacy gt with a 95 legacy engine swap require wiring changes? because im assuming he must have had to rewire things when he did the swap and possibly messed up on something there. I noticed a few wires such as my cam and crank sensors not the same color as what my haynes manual says they should be

Edited by Scotty1419, 31 August 2011 - 05:47 PM.


#4 johnceggleston

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Posted 31 August 2011 - 06:38 PM

My question is would a 98 legacy gt with a 95 legacy engine swap require wiring changes?


no, no re-wiring required.


because im assuming he must have had to rewire things when he did the swap and possibly messed up on something there.


i'm willing to bet on this as well. nothing is going to get the car to run right until this '' whatever'' is undone.

the wire colors under the electrical tape should be easy to figure out. but the connections should be soldered after you get them sorted out.

#5 Scotty1419

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Posted 31 August 2011 - 06:54 PM

i made a list of what i saw...

blk/red wire w gray lace spliced to 2 blk/red wires w gray lace

big red wire spliced to a little red wire w gray lace

blk/red spliced to gray

3 red gray laced spliced to 1 red gray lace

big blue/red spliced to little blue/red w gray lace

big gray and gray/red spliced to blk/red

big gray spliced to little white wire with gray lace

I also noticed that the cam and crank sensors had black and blue wires. and my wiring diagram says they should be blk/white

and my maf sensor has yel/blue w gray lace and a white and a pink w/ gray lace coming out of it and my book says it should have red/yel yel/blue and it says pink is for 1997 models only.

Im using the wiring diagram out of the haynes manual

#6 jarl

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Posted 31 August 2011 - 09:07 PM

I would stop playing with the harness before making a mess out of it. There's a good chance someone messed out it already, but just in case... :) (ask me how I know :) ) Have you (or your mechanic) connected an OBD reader to the car, to see what the ECU *thinks* is going on?

Now... If you swapped the whole engine -including ENGINE harness-, you'll need the wire colors from the donor car schematics -they may have changed-. Do you know which car did the engine come from?

As for the tape color... I've never checked a Subaru harness under the dash, but I think the two different colors may be OEM. The splicing looks suspicious, but still some of it may be OEM (i.e. there's a red/black cable splice at the ECU according to the wiring diagram). Without knowing where where those cables it would be hard to know. Were all those splices you mention right at the ECU? Can you take a picture, or somehow identify the connector/pin number? (attached is the pin numbering for the B84 connector, which I think is the one going to the ECU in your car).

I don't know how accurate is the Haynes for the Subarus, but I have seen big discrepancies on the wiring for some other cars. You should try to get the FSM for your car and for the car where the engine came from.

EDIT: I just saw your previous post with the OBDII videos, but I can't see much. Is any of the sensors obviously way off? Also, which color is the connector at the ECU?

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Edited by jarl, 31 August 2011 - 09:52 PM.


#7 Scotty1419

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Posted 01 September 2011 - 08:20 AM

Hey thanks for the help I just took some pictures and when i get the camera ill take a video that might help a little bit. hopefully you can see some of the splicing that was done. the gray splicing looks pretty factory looking but i dont think the black tape is factory. also i have used an obd2 scanner but i hear that since the swap was done the scanner might not be very accurate. i noticed the maf reading seemed kinda low

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#8 grossgary

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Posted 01 September 2011 - 09:09 AM

oh my what a mess! subaru's, particularly of this vintage, rarely (like, never) require wiring work like that. i'd definitely be checking those taped wires.

how many wires appear spliced/taped? do you have any idea why they did that?

the engine swap required no wiring at all. so whatever he did wasn't related to the engine swap....or shouldn't have been anyway.

misfire - have you considered the fuel injectors/supply? i had a really bad misfiring 2000 Forester last year. none of the standard things worked, swapping the entire intake manifold fixed it. not sure if that means fuel injectors or what but you might look into something like that?

#9 Scotty1419

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Posted 01 September 2011 - 09:12 AM

yep ive had the entire intake manifold swapped. Also i do know that my 6cd disc changer was put in. i dont know how much wiring that would have required but you would think that would all be behind the cd player and not the ecu? i counted about 8 splices all together, Im wondering though.. if its a wiring problem why did the car run fine the whole time i had it till i blew my engine then when he did the swap it it ran awesome for 6 months then all the sudden runs like ************. also i noticed a wiring harness thing that isnt even connected. its wrapped up in this foam stuff and it looks pretty factory. like it never was connected to anything

Edited by Scotty1419, 01 September 2011 - 12:02 PM.


#10 grossgary

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Posted 01 September 2011 - 09:54 AM

you're right - the changer shouldn't matter. a Subaru 6 disc changer, which it most likely is, are plug and play, no wiring required. even if it required wiring it wouldn't affect the car except blowing fuses or a drain, not engine issues.

given the running issues and known previous wiring attempts i think a simple test might help:

test for continuity and resistance on the wires between the engine side harness and ECU connector. this should be relatively simple - both connectors can be gotten to in 15 minutes or less, so rig up a tester and see what you get. you could even start with the 8 wires you've already identified as being previously compromised...seems likely you'll find the issue there.

or like a hacked up radio job you could *guess* and just re-do those 8 splices. pull the tape, pull them apart, properly join them together again.

#11 jarl

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Posted 01 September 2011 - 12:06 PM

yep ive had the entire intake manifold swapped. Also i do know that my 6cd disc changer was put in. i dont know how much wiring that would have required but you would think that would all be behind the cd player and not the ecu? i counted about 8 splices all together, Im wondering though.. if its a wiring problem why did the car run fine the whole time i had it till i blew my engine then when he did the swap it it ran awesome for 6 months then all the sudden runs like ************


You have an email, Sir...

Now... if you say the car ran fine before and after the engine swap that's very interesting. As I said before, I would stop messing with the wiring before doing something you can't undo.

To answer your original question: the right way of finding what's wrong is following Gary's suggestion. Look at the diagram, identify which pin on the connector goes where, and measure continuity between the connector at the ECU and the one at the sensor.

Cheers!

#12 nipper

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Posted 02 September 2011 - 12:13 AM

Just lurking.. but what a mess.

#13 Scotty1419

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Posted 07 September 2011 - 06:52 PM

wow what a day... i pulled the subaru out of the garage to get it ready to take it up to have a new engine put in and i decided to pour some seafoam in it... i put 1/2 in the oil and ran 1/2 thru the pcv valve.. car stops missing... take it for a drive and i got full power.. then my tach dies. car starts missing.. then straightens up.. then my speedo dies. at oil temp blinkin like crazy.. (14, 17 and 18 blinks) abs light on... Turn on headlights and car misses very badly like its going to stall .. take it up the road. car stalls wont crank.. had to jump it.. take it home car runs awesome and then stalls pullin it into garage. batterys dead. so pulled battery and its slow chargin all night... what a day! i cant believe its not missing anymore! im guessing the valves were sticking and the seafoam freed them up and thats why nothing would fix it(spark plugs coil sensors etc.) Anyways im anxious to put the battery back in the car fully charged and see what happens tommorow!

#14 987687

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Posted 07 September 2011 - 07:43 PM

Sounds like your alternator is dead. When you start the car if the battery idiot light and brake light stay on, something is wrong with the charging system.

I've driven on a dying alt till the bitter end trying to get home. And systems start just shutting down one by one like you described.

#15 jarl

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Posted 07 September 2011 - 08:27 PM

The dead tach/speedo suggest a bad ground or something like that. You can try something: with your volt meter on volts, see if there's any voltage between the battery neg terminal and the engine block or any piece of metal o n the engine. Try it also while cranking the engine.

You may want to check as well any splice done to install the cd changer. Sometimes the plastic crimp-on splices end up cutting the cable, even partially. Add some vibration and you'll get a very hard to diagnose electrical problem :)

Next time the car start acting up, check to see if the cd changer (or something else for that matter) stops working. Hopefuly it won't act up anymore, but just in case...

#16 Scotty1419

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Posted 07 September 2011 - 08:48 PM

well actually the battery light didnt show up. i think that the battery was just so far drained the alternator couldnt keep up and when i turned the lights on it just shot it over the edge.. also about the 6 disc changer, the 6 disc thing worked great when i first got the car of the guy. then a few months later it wouldnt work it would jsut spit them back out when i tried putting them in slot 1 - 6. so i have only been able to play one cd at a time in the top cd slot.. any ideas as to why its doing that?

#17 Cougar

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Posted 09 September 2011 - 10:03 AM

Make sure the battery warning light turns on when you turn the ignition switch from OFF to ON. If the light doesn't work then the alternator will not work either. After reading your descriptions of the troubles it sounds like you may have an alternator or engine grounding issues.




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