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Old 03-20-2020, 08:39 PM   #1
Scooby Newbie
Member#: 511272
Join Date: Feb 2020
Default 2004 STI Speedo troubles

Hi everyone so first and foremost ive scoured the internet for a fix here and i just cant seem to find it so if i passed over something our i didnt dig deep enough i apologize ahead of time. I have a 2004 STI that is sitting at 44,000miles and i bought it about 6,000 miles ago. recently the speedo stopped working sortof and it acting weird. originally i thought it was liquid hitting a wiring harness and i still think it but am unsure how to address it. about a month ago the speedo started jumping up and down and sometimes not working all together. but i have a cobb accessport and the accessport read the Vehicle speed just fine with no worries. it seemed like this would only happen in rainy/snowy weather or after the car was washed that day. when the car was dry i never had any troubles. well about a week ago both speedos stopped entirely nothing would tell me my speed. i replaced the Vehicle speed sensor on the transmission and im back to step one. the accessport will always read the speed with no issue what so ever and if the car is wet the main speedo will bounce around or not work. i have a front mounted intercooler so my hood scoop does leave quite alot if area open to the elements but i dont understand why the car would have so much trouble being wet. i even need to place towels in the scoup to block out water or sometimes the car will not even start due to the water on the wiring. ive looked at the wires up and down and dont see any exposed innards. is there a specific place i should look? or should i replace something in particular? any help is super appreciated!! thanks
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Old 03-29-2020, 03:30 PM   #2
Scooby Newbie
Member#: 435611
Join Date: Dec 2015
Chapter/Region: International
Location: Nairobi
2002 SG5-2.0-XT-JDM
45A, originally 18L


why assume it is wet when all the wiring is unexposed as you say?

have you removed the speedo cluster and checked for a loose fitting cable? have you followed that cable to where it connects? and if not the cable, maybe the actual speedo pins are loose....?

i suspect something lose because jumping up and down would infer touch-release interference. OR, at the ecu location something is loose.

i always say, if when washed something happens e.g, CEL, bucking or anything untoward, then something needs to be tightened, hidden or replaced.

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Old 03-29-2020, 04:14 PM   #3
NASIOC Supporter
Member#: 90539
Join Date: Jul 2005
Chapter/Region: South East
Location: Lake Charles
My BOV goes


If the accessport is reading speed, the speed sensor works.

If you have a sunroof, maybe check and see if its drain in the front is somehow wetting the wiring on the driver side, or maybe the passenger side near the engine computer. Some vehicles have four drain hoses, one on each corner.

Other than that, could it be coincidence and the speedometer motor is actually faulty?
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