Retrofitting an Electronic Flasher Relay

[hegedus]

Written by Chris Blumenthal Friday, 30 September 2005 Retrofitting an Electronic Flasher Relay

By Chris Blumenthal

Introduction

Most 02 pilots have experienced turn signal problems. The dreaded indicator light "no-blinkie" and flash-only-once syndromes are among the most common. Another symptom is the fast-flashing indicator. Most of these problems seem to be traceable to excessive resistance in the turn signal/hazard flasher circuit. The '02 turn signal/hazard flasher circuit is notoriously sensitive to bad connections (both - and +) and poor quality bulbs causing too much resistance in the circuit.

About 6 months ago, my instrument panel turn signal indicator started working intermittently and finally got to the point where it would only flash once when I first applied the turn signal, even though both front and rear bulbs were flashing as appropriate. I went through my whole system, cleaning up the contacts and grounds, and replacing a couple of brass base bulbs with the supposedly preferable "silver" base bulbs (available from the dealer and aftermarket sources from manufacturers Sylvania/Osram or Philips [others?]). When this didn't fix the problem, I replaced the flasher relay. This fixed the indicator problem, but the flashing (both the indicator and bulbs) was about twice as fast as the original and normal speed... not quite as fast as when there is a burnt-out bulb, but way too fast. Reminded me of the turn indicators you see on the typical death car or '63 VW bus. This just wasn't right for a dignified '02.

The only direct replacement relays that I could find were marked "XS," with the X overlaying the S. It is my understanding that these relays are made by Siemens. A quality manufacturer for sure, but all of the OE relays I have seen were made by Hella. I have since tried a few different, used Hella relays lent by friends, but all have exhibited the original indicator blink-only-once problem. My conclusion: something beyond the normal and obvious is screwed up in my flasher circuit, probably in the wiring. I guess I could have lived with the fast flash problem, but it really bothered me.

The Solution

A few months ago, I happened across Zenon Holtz' web site. Zenon is an '02 brother from the Great White North (well, not so white in BC...) who has a nice BMW related web site, including a discussion (under "tech/troubleshooting turn signal problems") of using a generic, 3-prong turn signal relay in the '02. This got me thinking about using an electronic flasher unit in my '02. I knew from non-'02 related experience that electronic, variable load (resistance) flasher units are available for a pittance (<$5). Besides the low price, the other benefit of using for a generic electronic flasher relay is that external conditions do not determine flashing speed, which is electronically and internally regulated by the relay assembly. In fact, the "variable load" designation means that the flasher will function with different wattage bulbs, variations in circuit resistance, etc.

Get a 3 prong flasher unit with terminals marked "X," "P" and "L." There are different spec units available. Littlefuse makes a unit designated "EFL 300" that is appropriate- if you cross reference to that, you will get the right part. The X terminal is the +12V input, the P terminal output drives the flasher indicator in the instrument panel, and the L terminal drives the load (bulbs).

In the '02, the typical flasher wiring is comprised of a 4-wire circuit, including the following: brown (ground, of course), black/white (instrument panel flash indicator), green/violet (+12V) and green/yellow (load- bulbs). The brown ground wire is not used with the electronic flasher. The configuration of the male spade connectors on the flasher unit is very similar to a headlight connector. A female headlight connector with pigtails (available at most any auto parts store) works fine as an adaptor between the 3-prong electronic flasher unit and the '02 flasher connector. Note, however, that for a few bucks, many auto parts stores can provide a more precisely fitting plug intended specifically for turn sign flashers.

Just solder .25" male spade connectors to the pigtails (use shrinkwrap to cover your solder connections, of course) and plug into the '02 connector. Connect the "L" terminal to the green/yellow wire, "X" to the green/violet wire, and "P" to the black/white wire.

Conclusion

So, why do this? (1) Endless, cheap source of flasher units; (2) flasher is unaffected by and insensitive to slight variations in resistance in the old '02 wiring; and (3) nicely paced, perfectly timed flashing (again, regardless of slight variations in resistance in the circuit).

Although these flasher relays works with variable resistance, this setup will alert you to a burnt-out bulb by increased flashing speed like the original, non-variable load '02 flasher. Note: I am not advocating this as a solution for poorly maintained '02 flasher circuits. Use good bulbs, and keep your grounds, connectors and bulb contacts clean!

If you have any questions, feel free to post them to the Message Board!

 

 

 

 

 

 

 

 

 

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[73touring]

The Teltail light in the dash doesn't seem to work with this arrangement for me. Anyone else had this experience

[speedyshel]

I know this is an old post, but it worked fine for me.

[bahlvin]

I had a similar issue as 73touring that I was able to resolve. I had trouble finding the EFL 300 mentioned above so I went into my local O'Reilly auto parts store to see if they had a flasher that would work. Their system pointed me to a 3-prong flasher with terminals labeled "+", "-", "L".  I bought the flasher and tried to make it work to no avail... no matter which combination of three wires were plugged into the leads, the dash indicator never worked (although the flashers themselves were functional). I returned the unit, did some more sleuthing online, and found www.memotronics.com where I ordered an EF33 flasher unit, which has terminals "X", "P", "L". Plugged it in as specified above and it works like a champ.

[GregF]

@bahlvin: Did you buy the EF33 or the EF33H from memotronics? was it as simple as just plugging in to replace the old relay?

Thank you,

 

Greg

[wh400]

I have used this method - works great...

https://www.bmw2002faq.com/articles/technical-articles/electrical-and-ignition/refreshing-the-3902-flasher-relay-r57/

 

[Chris_B]

The old guy is still around (and still has his 02), if anyone has any questions about this FAQ. I am sure there are products available that are equivalent to the "EFL 300" that I used.

[4speeder]

I've had the 2-or-3-blinks in the dash for a long time, and with no auto-off I did an embarrassing amount of driving with the signal on. Just performed this fix and the dash indicator works! Fantastic. The switch I used is from amazon:

 

http://www.amazon.com/gp/product/B00206JCTM/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

 

Thanks for the tip!

[steve k.]

worked like a charm!  Thanks!

[Chris_B]

I am very much into using LED bulbs in my cars now. They are so much brighter than incandescent bulbs, and consume much less power. The other advantage is using red or amber LEDs will really make those faded 02 taillight lenses look clean and clear again. Another benefit is that the you can have taillights that match modern vehicles in brightness.  Any 02 turn-signal circuit will exhibit the fast flash because of the lower resistance of LED bulbs. If you want to keep your original flasher (presuming you had no problems before the LED conversion), you can add a resistor to each circuit to compensate.   Fitment can be a problem, because some LED bulbs are really long and won't mount in an 02 taillight,

These are really cool, because they fit like original 1156 bulbs, but are many times brighter:

http://www.ebay.com/itm/271890419060?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[dpowell]

So glad for this posting!

I just performed this swap, minus the pigtail. Just three short equal lengths of 16g wire with male spade disconnects on one side and female on the other.

 

Thanks for saving me time and money!

[Wahnsinn]

This is what is so great about this site. I typed in "turn signal indicator light stays on", and found this solution, which worked great.  I bought the NAPA EL-13 flasher unit pictured, and everything worked exactly as described.  

 

Thanks to all who contributed.

[Dudeland]

Just installed the EL13, works great.  I took the bracket off the old signal (ground of the rivet) and mounted it upside down on the on the flasher.  That way the bulky wires and relay plug are tucked up under the dash, don't hang down as well as keeps the relay in place. 

 

 

FYI be careful not to go by the wire color on the relay base plug.  Mine had the identical colors but in different positions. 

 

 

 

Edited September 13, 2017 by Dudeland
Update

[chargin]

Add On:

If you are converting to LED Taillights the one that actually works is:

https://www.amazon.com/gp/product/B0031GWPGC/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

 

 

 

 

It took me 6 different units until I found this one that actually works both Turn Signals and the Dash Indicator light.

 

 

 

['76mintgrün'02]

My OE flasher wasn't doing its job, so I took the cover off and cleaned these contacts, using the back side of some sand paper.  You can see the black crud that came off.  It appears to be working as it should again.  I feel like I got lucky.  This might be one last thing to try, before tossing it in the neighbor's pool.