Signals not working properly, which part do I need?

2007 KIA SPECTRA
75,000 MILES
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SPECTRA HANSON
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Left blinker light did not blink; it stayed on after car is off and key removed. Battery drained overnight. After charge and 45 minutes idling, I drove to friendly mechanic. At that point the blinker blinked, both on taillights and interior dashboard indicator. Mechanic checked bulbs, etc. Problem seems intermittent.

Internet search says replace blinker relay switch. Kia parts dept says there are two relays, and since its unknown which failed, replace both at $30.00 each.

Another internet search mentions BCM--Body Control Module. Kia parts guys says get BCM at $525.00, but did not know if BCM contains the Relay switches he recommended replacing.

If we replace Relay switches, where does Relay switch go?
Is it a component of a new BCM, if we go that route? or is it something distinct from the BCM?
do we need BCM and Relay switches?

Thanks in advance for the help.

Bob Hanson
Nov 16, 2021 at 10:53 AM
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KASEKENNY
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Technically they are both correct. This most likely is a relay issue but these relays are integrated into the BCM. The issue we have is that this is intermittent, but it does sound like the relay just stuck on.

So as of now, if this is not acting up then there is no way to prove it was the relay and not the turn switch.

So, if it were me, I would not replace the BCM without knowing that this was the issue.

If we can get this acting up again then we need to simply check the voltage from the switch to the BCM on the gray wire. The wiring diagram is below to help with this and here is a guide that shows this type of testing.

https://www.2carpros.com/articles/how-to-check-wiring

If there is voltage on this wire, then your switch is closing the circuit and it is the issue. However, if there is no voltage then the BCM/relay is keeping the lamp on.

If this is a relay, it will most likely happen again. However, there is no guarantee it will happen again so if it were me, I would wait until this issue gets worse so that you are not replacing the BCM for no reason.

I attached the info below for your review. Please let me know what questions you have, and we can go from there.
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Nov 17, 2021 at 9:42 AM
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SPECTRA HANSON
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Thank you. We were leaning in same direction you suggest, i.e., hold off replacing BCM until we know for sure it is the problem. I printed out your diagram and link and will take to mechanic who can run the diagnostics you suggest (electrical is beyond my capability).

bob
Nov 17, 2021 at 1:23 PM
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KASEKENNY
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Okay. Sounds great. Thanks for the update and please let us know what ends up happening or if there is something else, we can help with. Thanks
Nov 17, 2021 at 6:52 PM