Front Directional Signal Out…Rear Blinks Rapidly

[OK-944]

My 87NA’s left rear directional bulb blinks rapidly while the left front does not blink at all - but the parking lights work fine.

I’ve cleaned the left rear grounds (left front grounds done recently and look fine). I’ve removed the (new) front directional/parking light bulb and cleaned contacts inside the socket.

I’ve pulled the front directional/parking electrical boot off from underneath and cleaned those contacts.

Fuse #31 (left directional fuse) looks to be fine, and I replaced with a spare anyway with no change.

So…I have two thoughts on this:

One - that I need to re-remove the front boot and peel off the badly cracked protective rubber, and check the connections now visible and clean/re-solder/re-attach or whatever - then wrap with electrical tape and reinstall.

Two - thinking that the rear directional bulb needs to work properly in order for the front one to work…I’ll remove this rear bulb, clean it and its socket, and re-install.

Finally…I’m guessing that the directional signal relay is fine - otherwise I’d either get nothing from either side or one or more of the blinkers would just stay on and not blink.

Pulling my hair out about this (car due for state inspection) - and am open to suggestions. Thanks!

[originalowner]

Left front bulb burned out? If not, check for blinking voltage at bulb socket to confirm wiring is intact.

[Monkey Wrench]

the blinker relay is a bimetallic strip in seriies with the bulbs for left ot right.

a bad ground ( or weak hot) causes increased circuit resistance because the bad connection is in series with the bulb.

then the bulb glows dim, its sharing its voltage ddrop wiht the poor connection and therefore seeing less volts.

since the circuit has increased resistance, ( the power is going throiugh the filament plus the bad connection) then the relay is seeing reduced amperage.

it blinks slowly then becuse there inst as much electricity flowing through the bimetallic strip. (the circuit is runing less amps than normal)

i ordered a half doxen bulbs fron ahem! rock auto and recieved 6 boxes of 12, theywre so cheap I had not noticed my error.. and I was actrually happy because they were incredibly cheap, I guess there is a glut of incandescentts in some warehouses. You can fill your boots with them ;-)

the relays can wear out they are usually pretty standardized or at least were, before wiring for signal lights involved LED's and thinner wires

using the wrong bulbs or LED's can change the circuit resitance and electrical flow ( amps) through the bimetallic strip .. it needs to heat up at a regular rate or the signals blink the wrong speed.

when the strip heats up the contacts open, then there is no heat generated and the metallic strip bends back as it cools, it closes the circuit . then it repeats. thoise contacts might not actually run the lights, they run the coil of the relay. thats why it clicks , i guess the relay coil is turned on and off by the intermittent power from the bimetallic strip.

Ive seen two kinds , eiuther 3 or 4 prong. maybe there are different ones for different loads but many cars seemed to use ones that were interchangable.

I wondered why the speed would change if the bimetallic strip is only powering the relay coil and not actually the lights. It may be beacue that cuircuit ( the relay and the bulbs) is all fed from the same fuse..

is that clear as mud?

maybe someone can explain it better.

[OK-944]

So if the blinkers depend on a heating filament within the relay to heat up and make contact, then I’d guess that if one of the two (front and rear, same side) blinkers were removed from this circuit due to a short…the relay filament would heat up more quickly due to less resistance from just the one bulb - so this bulb would blink more quickly. Therefore I’m guessing that the relay is fine.

Further muddling the situation - The Sylvania “replacement” bulb does not work swopped out with the existing working bulb on the “working” side of the circuit - nor does the working bulb work on the “bad” side. So I could have two issues here. The only approach I can think of at this point is to re-remove the torn directional assembly boot completely and really “deep clean” any possible corrosion. Beyond this…I’m wondering about the routing of the grounding for this circuit - which from my understanding runs to the left rear of the car…and that perhaps there is a break in this someplace. Hmmm…should try a short jump from the front ground to metal to test this out. Make sense?

Seems like this should be easily solved. But then again - automotive electrical diagnosis has never been my strong suit.

[djnolan]

I think it is a dual filament bulb for the turn signal and the parking light. If the parking light is working then the ground is ok since both circuits share the same ground. So your problem is on the positive 12v side of the turn signal. before tearing it apart check for voltage on the bulb socket. it might just be the bulb is loose or the contact is pressed in or stuck or dirty because of dried grease. Lots of folks use grease to protect the contacts form moisture but eventually the grease hardens and causes problems.

[Monkey Wrench]

yes dotn confuse parking lights and signal lights , thats a different cuircuit, it may share the ground..

you can always try a hunk of wire from battery negative to any ground point, if duplicating the ground changes things , then you have a bad ground.

the blinkers on the left side ( one fron t one back) are run in parallel to one another, as are the right side blinkers.

two bulbs in parallel both share the electricity, so the second one lowers resistance by adding a secondary current path.

if bulbs were run in series , then if one bulb burned out the other would go out too, so it wouldnt be wired like that.

if one bulb burns out you only have the one left working, so then the resistance is higher, the curremt has only one path and not two.

higher resistance means less current flows.

less current means the blinker takes longer to heat up and so it runs more slowly than it should.

definitely clean the sockets and clean or replace the bulbs. if youneed a new rubber boot for the lens so be it , maybe you can glue it up

Id unhook the battery you can use a little ball of steel wool to clean in the socket but just make sure you get any fragmets removed before connecting power.

steel wool will burn, it will actually flame up if you short circuit through it.


when the boot is damaged it traps water inside.


signals often share the same little relay, and the right side may use the same relay as the left side
to put on connections and bulb sickets you might try this product..

https://sw-em.com/anti_corrosive_paste.htm

theres lots of good stuff on this swedish embassy site so if you dig around a lot of the knowledge is quite good.. heres a bit about cleaning up bulb sockets for a 122 ( AKA amazon)

https://sw-em.com/Amazon_Rear_Light_Fixture_Restoration.htm