Indicator problems
 

Hi all,

I'm hoping someone may be able to help with a problematic indicator.

Basically, my RH front indicator illuminates but does not blink and the corresponding rear lamp does not illuminate at all!
Both LH lamps operate correctly.

Thinking it may be a problem with what I found to be a corroded bulb housing, I replaced it but with no luck, the RH front is still just constantly on with no blinking.

Any help would be greatly appreciated.

You may have to get the rear indicator working to have enough current flowing through the flasher unit to heat up the bi-metal contact and make the lights blink.

I think gjr0 might have the answer. There are two versions of the two terminal flasher relay.

One style has a resistive wire in series with the bulbs that heats up a bi metallic spring and causes the relay contacts to close. The contact closing illuminates the bulb with full voltage; but, also passes the resistive heating element which starts cooling down and pops open the contacts turning off the light and sending current through the resistive heater again to repeat the cycle. If you have insufficient initial current to heat the resistor this relay will fail to turn the signal light on initially because the contact never goes closed because of

The second style works similarly; but the relay contacts are initially closed and light up the turn signal bulbs right away. In this relay the resistive heating element is energized and heats up the bi metallic spring when the contacts are closed (bulb illuminated). When the bi metallic spring heats up it bends and opens up the contact shutting off the resistor which allows it to cool and the contacts to close.

If you have the first style relay, insufficient initial bulb current will result in the contacts not closing and the front turn signal should not operate. Since your front turn signal illuminates continuously, I expect that you have the second style relay. However, I expect that you may have two problems. This type of relay should have a form of hyper flash when one bulb fails. Because of the lower current with one burnt out bulb the heating resistor take longer to pop open the contacts and the contacts close back faster resulting in a long 'on' followed by a short 'off'. This hyper flash is actually a design feature and is a regulatory design requirement in North America. It seems like your single front bulb is not drawing enough current to heat the resistor to pop the contact open. This could be caused by
- you front signal light sockets are similarly corroded to the back resulting in a high resistance connection
- you have the wrong (low wattage) bulbs or LED bulbs up front
- your turn signal relay has seen better days.

If your right rear is not illuminating at all and you have correctly replaced the socket, then you have a wiring issue in the circuit to the right rear light. Mr. Ron K has conveniently provided wiring diagrams for the Amazon.

https://www.sw-em.com/Wiring_Diagram...Wiring_Diagram

Since your right front turn signal illuminates, I suggest that you start checking those junction connectors shown in the wiring diagram which connect the right rear to the common junction to the right front which we know works.

Many thanks indeed for all the info guys.

Right, so I've checked the bulbs and they are all good.
I found the green wire leading to the indicator bulb on the RH rear had come completely adrift! so I re-fitted it.
I now have a long 'on' followed by a short 'off' both front and back, also the lower bulb for the main lights also flashes but very dim and weak.
If I turn the main lights on the indicator goes off!

The long on followed by the short off if an indication that the total bulb current on the right side is below normal. I assume that the left side has the normal on-off pattern?

Given that the tail light bulb appears to be illuminating I think you might have a failed ground path issue and that the return path for the signal light bulb may actually be occurring through the tail light bulb in series. The frame of the tail light assembly has to be solidly grounded to the body to form the return path for the signal light bulb. The wiring diagram infers that there is jumper wire on the signal light housing to form the ground path.

10 years ago I did a bare body restoration on my 140 with a new coat of paint over everything. As I re assembled the car I was testing out the individual electric systems. When it came to the running lights, signal lights and brake lights I had much electrical weirdness. All of this was traced to a fresh coat of paint interfering with the ground path. Scratching off the paint for a good ground resolved everything.

If you had corrosion on your tail light housings I expect that you have other electrical issues at the grounds and those terminal blocks. Vintage Volvos are not spectacularly water resistant. Careful inspection and some preventative maintenance may be in order. Refer to Mr. Kwas' discussion of zinc bearing grease
https://www.sw-em.com/anti_corrosive_paste.htm

Turns out it was the relay, fitted a new one and all's good :regular_smile:

Thank you so much for all the feedback and help

That is curious. It is unclear how the lights could operate normally on the left side and not function on the right if it was a flasher relay problem. Perhaps this car was previously owned by a labor MP and always turned left? :regular_smile: