Welcome to the forum.

Is this a car you've just bought? If not, how did these faults develop?

BCMs are a common failure on GK Coupe/Tiburon. We've just resolved a turn signal fault on another one that was down to a failed BCM...link below:

Tiburon - whole right side turn signal dead

 

I just bought it, it has 69,000 miles. And kids kinda hacked the stereo harness up. I thnk they tried to hook an amp up from the cigarette lighter. I fixed that and pulled the whole ashtray assembly from a wrecked car and plugged it in, done away with the bare wires. Pretty sure they just wanted a racing steering wheel so they pulled the original. I didn't have cruise or an airbag anymore plus everytime I turned the wheel I was turning on the wipers, very aggravating. So I pulled the whole column from a wreck car with a good airbag. Thought the different signal switch might fix my problem, but it didnt. Found a blown lp fuse figured that would have fixed my taillights since it restored my interior lights, but it didn't. Lol Need some professional advice. What do the internal bcm relays correspond with? Just something off the wall I noticed when I turn my ac on and the cab recirculating lights are lit up they flicker. Just thought id mention that.
Thanks in advance,

 

There are three relays inside the BCM. Two are for the turn signals and the parking/side lights, the two things that aren't working on your car funnily enough. I'm not sure what the 3rd one is for.

You say you don't hear any relays clicking inside the BCM. Do the hazard lights work? If not, try replacing fuse 7 on the dash fusebox/BCM. That's the fuse that supplies power to the turn signal relays. If replacing the fuse doesn't help, check that there is a 12V supply to the fuse itself.

 

Ok, I'll will try that. I have a 12 volt light tester at home. Does the key need to be on? And does the signal need to turned on before touching at light tester to fuse 7 slot? There is a guy that rebuilds bcm's on eBay for 70 bucks. I just have to mail him mine. Says he puts better parts in them. I work a lot so I can pay someone to do the installation of the relays, plus they will probably do a better job than me. I need to check the rear bulbs before hand to.

 

Ok, I'll will try that. I have a 12 volt light tester at home. Does the key need to be on? And does the signal need to turned on before touching at light tester to fuse 7 slot?

It's a constant 12V supply on fuse 7 so the ignition doesn't need to be on and you don't need to switch on the turn signal switch.

 

I'm really curious if that third relay has anything to do with the thermostat settings on the heater/ ac. It switches fine from defrost to floor etc.

 

There is a bcm in that car I got all the parts from think I should take a chance and buy it for like 20 bucks? The yellow room 'll fuse holder has been yanked completely out

 

think I should take a chance and buy it for like 20 bucks?

I think that would be a good idea. If it turns out not to be the BCM that's causing the problem, I'm sure you'd easily get your $20 back if you put it on ebay.

 

What about the room lp fuse holder? It's missing can I place mine in it? And that car is a automatic gs mine is a manual shift gs. Same engine and same year would that make a difference?

 

The yellow fuse carrier isn't really needed. It's only used to isolate the circuits that are connected direct to the battery when the car is in long term storage. I don't think the gearbox will make any difference to the BCM.

 

$20,, the BCM (I/P junction block) been through a pile of part number change so many time it aint funny,, and it $750+ for a new one, and who know if it any good for how long..

 

and it $750+ for a new one, and who know if it any good for how long..

If you don't know if a new one is any good or how long it will last, you'd be as well to take a chance on a $20 used one. It can't be any worse :smile:

 

Got it for 10.00 just now got back with it

 

I pulled everything practically from it the other day, but I have the fuses and relays here with me. Im about 6 hrs from home working. Anyone have some pictures for me to replace everything correctly. Im in a motel and bored....lol

 

Anyone have some pictures for me to replace everything correctly. Im in a motel and bored....lol

I already posted a photo of the fuse locations earlier (post #4 ) and I don't think you can mix up the relays.

 

Thanks Auto, I remembered that afterwards and felt silly. Actually it is the relays on the back, I have some blue ones with 5 pins and some with 4 that will go in the same slots. Those two blue relay slots on the back of the bcm are made with 5 pin slots. I looked down inside looks like the only 4 outside pins have metal connections which probably just answered my own question. I just wanted to make sure. I got a few from under the hood mixed up with the bcm relays. I guess I can just look at mine when I get home.

 

I looked down inside looks like the only 4 outside pins have metal connections which probably just answered my own question.

Yeah, it's 4 terminal relays that fit on the back and the little white one that only has 2 terminal (it's actually a diode, not a relay that one)

 

Thank you auto. Im gonna check fuse 7 and hazard lights tonight when I get home. Whats the next step? Lets say I have voltage at 7 and the fuse is good, but no signals. Or lets say I have no voltage on fuse 7. I have very limited time at home before I leave again.

 

If there's voltage on fuse 7 but the turn signal relay doesn't click inside the BCM, then the circuit inside the BCM between the fuse and the relay might be open/broken. You'd need to open the BCM to investigate.

If there isn't voltage on fuse 7, try jumping a wire between a fuse that does have 12V and fuse 7 to see if that gets the turn signals working.

 

Will do thanks for the quick response.

 

Ok, so I have voltage on fuse 7 and the fuse is good. I have no hazard lights and no voltage going to the hazard lights. I guess the next move would be to pull the bcm and open it up and look for a open circuit between fuse 7 and the relays.

 

Or maybe I should just hook up the $10 bcm which I have ready to go?

 

The switches inside the cabin in these cars typically switch ground.

Now, we did have another person here with a similar problem, and it turned out it was the BCM for sure, but...you don't want to plug (what you hope is) a good part into a bad circuit. Now, $10 isn't anything to cry about, and if it blows you're out $10, but...

I would have a look at the grounds before swapping it. Hyundai engineers seem to have truble with the concept of ground, and really don't go an extra mile with them. I would have a look at the switch and see what's going on there, and also check the grounds at the BCM and around the cabin and the engine compartment. Just to make sure. After chasing the grounds down I'd plug it in and try it.

Of course, I would also see if I could get another BCM for somewhere around the same price, and if I could I'd plug 'n chug and cross my fingers. If it works, you're done! If not, then go through the grounds and get another BCM.

Also, from the other thread, it seems the BCM has an issue with moisture coming from somewhere, so I'd also try to waterproof it better before installing it.

 

I already hooked it up. I have taillights, dash lights, and now hazard lights. But when I turn the signal on it fashs Luke I just kicked the hazard lights on. They blink simultaneously same speed same time and my lights are working in the back. Signal and tail. Hopefully I haven't messed something up.

 

They blink simultaneously same speed same time and my lights are working in the back. Signal and tail. Hopefully I haven't messed something up.

What I'd suggest at this point is you disconnect the all the lamps front and rear. Now switch the turn signals on and see if both the left & right tell tail lamps on the instrument cluster come on together. If only one side comes on it looks like there is a short in one of the lamps.

 

I believe that maybe that bcm had signal issues as well. Idk Better than what I had.lol

 

I did notice a wire ran from both taillights. Its definitely not factory. I just now remember seeing that. So unplug all bulbs from front and rear taillamps

 

No need to remove the individual bulbs. Just disconnect the harness connector from each lamp unit.

 

Ok I disconnected all the lamps and the signal lights work. They start with a slow blink then kinda fast. I'm guessing because they are disconnected. But it does the same left or right. Normal blink then speeds up to a faster one.

 

When the lamps are disconnected do the turn signal warning lamps on the instrument still both come on together or only the the one for the direction you set the switch to?

 

I see no warning lamp light on the dashboard. They just blink normal then speed up to a steady fast blink. Dosent matter which direction. But I found a jumper wire ran to both taillights it ran from one to they other. I disconnected it taped up the bare spots used to jump the wire. I then hooked up the parking/signal lights and it's working perfectly now. All lamps besides the license plate lights work. It fixed it, and I couldn't have done it without you! I guess my numbers came in on that junkyard find. Hopefully it will last awhile. I noticed that the cigarette lighter has a light around it, but it disappeared. The ashtray light still works.

 

Thank you very very much everyone!!