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Erratic turn signal flasher relay

br1anstorm

NAXJA Forum User
Location
United Kingdom
I have a strange problem on my stock 1993 XJ. The turn flashers are behaving erratically.

I've done a quick forum-search and was astonished at how many issues there seem to be with turn signals/hazards/flasher units. But none seems to show the same symptoms as I have.

When indicating to turn either left or right, the flashers go bright-bright-dim-dim-nothing-bright.....and so on.

I did the obvious checks. The hazard circuit works fine: regular bright flashes from all four bulbs. So the bulbs are all fine, their connections are fine, and the hazard relay unit evidently works.

So I assumed the original turn signal flasher unit (relay) in the fuse panel was simply tired or worn out. It's a Wagner 552, two pins.

I got a cheap standard (unbranded) replacement, and fitted that. Dang me, the new flasher unit performs exactly the same: still the erratic flashing pattern when turning left or right.

So I'm baffled. I understand there are two types of flasher relay unit - thermal and electro-mechanical - and that they are interchangeable. No idea which type my original unit or the new one might be.

What else might be causing this problem? What else can I check?
 
Could be the actual turn signal stalk in the multifunction switch or its connector contacts? If you do replace it, I recommend the Mopar one, the aftermarket I got was terrible.
 
A quick follow up. I tried another trick picked up from a thread in this forum.

I swapped over the hazard flasher unit (Wagner 224 - which is a 2pin circular blue plastic drum-shape module) with the turn signal unit (Wagner 552 - a 2pin shiny aluminium drum-shape module).

Well..... the turn signals flashed nice and bright and regular, both left and right.

And the hazards ..... didn't work at all.

So the original Wagner 552 turn-signal flasher relay seems definitely to be faulty. The weird thing is that I then put my shiny new unbranded flasher unit into the hazards socket. Didn't work. Is the new one faulty too? Very odd.

But at least this confirms that it's not the multi-position steering column switch assembly that is to blame.
 
Nice. The new one could certainly be faulty or just not built to spec. If its easy enough just try another one and if it doesn't work look for a better quality flasher.
 
Oh dear. This problem gets more puzzling.

On the evidence so far, I have proved that the Wagner 224 (blue plastic casing) flasher unit, which originally controlled the hazard lights, is working properly. It makes the hazards flash; and if plugged into the turn-indicator circuit, it makes the left or right indicators flash properly and regularly.

The original Wagner 552 (aluminium) unit for the turn indicators was making them flash feebly and erratically. So I replaced it with a new unbranded unit. This was no better, and produced the same erratic flashing. When I tried each of these in the hazards circuit, neither made the hazard lights flash.

So..... I got another new flasher unit. This one is labelled 'electronic' and 'heavy duty'. Guess what? When I put it into the indicator circuit, it doesn't make the turn lights flash at all. And when I put it into the hazards circuit, it either illuminates all four lights permanently (no flashing) or doesn't light them up at all.

What is going on? The Wagner 224 flasher module operates either the hazards or the turn indicators perfectly normally as it should (which suggests that the bulbs, wiring and connections are all OK). The original Wagner 552, the aluminium unbranded replacement, and the heavy duty electronic unit, don't work the turn indicators (either erratic and feeble or nothing) and they don't work the hazard lights....

I can't keep getting more and more replacement flasher units until - like a lottery - I find one that works. (Wagner modules seem not to be available in the UK market). On the evidence so far, I can't see exactly where the fault lies, nor how to fix it.
 
Any chance of getting some OEM ones out of a junkard?
 
The most common problem is the ground. When the ground has excessive resistance the flasher can get erratic. Corrosion can also be an issue, either on the hot side or the ground side.

Another issue can be matching the flasher unit to the number and wattage of the bulbs. The universal units seldom work out well. The flasher unit on some imports is a mismatch anyway as the side marker lights are disabled on some import models.

Just a couple of things to look at if it isn't an easy fix.
 
Thanks for those helpful thoughts. On the junkyard option, not much hope - finding an XJ of about the right vintage in a UK junkyard is needle-in-haystack stuff..... but I will hunt around.

Checking the grounds of the circuit(s) is a logical route to follow. But I confess I'm just not exactly clear where any ground-connections might be. All the turn indicator bulbs have two-wire connections, so the grounds must be (or could be) anywhere else in the vehicle. I don't think there's any corrosion around or behind the fuseboard panel into which the relay modules fit. All the bulbs do light up: I admit I haven't yet gone around the vehicle and dismantled all of the light-units and examined the bulb-sockets and wiring connections....

And it's not as if one bulb, or one side, flashes erratically (which would suggest a suspect or corroded contact). If the problem was a slightly bad ground connection somewhere, how is it that the original hazard relay unit (the Wagner 224) not only makes all the hazard lights flash correctly, but also makes the turn indicators work perfectly when plugged into that circuit? To me that says that the circuits (and the ground connections) are good. Meanwhile neither the original (faulty?) turn-signal relay nor the two different new ones can make either the hazards or the turn-indicators flash properly, if at all. That seems to point to the relays themselves not operating properly, though it still seems long odds that three different units (the original and two replacements) should all be incapable.

Although I'm in UK, my Jeep is a stock LHD US-spec vehicle. Maybe the new universal units I have tried are incompatible with the number or wattage of the bulbs, or the wrong spec. But something like a flasher relay unit or module is surely neither complicated nor unique? Rock Auto and other sources seems to suggest that any of the different manufacturers' units are all suitable and interchangeable.
 
Did this erratic behavior start recently, or has it done this for as long as you've owned the vehicle? If it's always done this and you're not the original owner, maybe the type-552 never belonged there in the first place and someone just jammed it in there to fill the hole. I know you don't want to keep buying parts, but it seems like the quick fix would be to get another 224 and use that, since you already know that one does the job for turn signals too.

Does anyone know if there was any change in the flasher parts over years, or if the flashers from the later models are the same? It's not like the factory ever equipped an XJ with LEDs...
 
That seems to point to the relays themselves not operating properly, though it still seems long odds that three different units (the original and two replacements) should all be incapable.


I'm with you here. If the grounds were bad I don't believe any relay would produce the correct behavior. The relay is the issue, the question is why. Either the demands of the circuit are different from what the relay is speced for (e.g. non stock bulbs) or the relay is out of spec, imho.
 
This is turning into an interesting discussion!

Rob - I've owned my stock XJ from brand-new. 26 years and some 160k miles, but mostly on-road (or when off-road in desert sand, not mud and rocks). So it's been well-treated and maintained. It is now basically showing signs of age: I've replaced the usual things but nothing serious. Both those Wagner flasher-relays (the 552 in the turns and the 224 for the hazards) are the original factory fits from new. The erratic behaviour started just a few months ago, not just suddenly one day. We just became aware that the turn flashers seemed a bit irregular. That's why I thought it was just the turn-relay (the 552) dying of old age!

It does look like a relay issue. But to find two different and supposedly compatible new replacements, one looking identical to the 552 and one electronic heavy duty (with clear plastic casing) producing almost exactly the same erratic flashing pattern (or nothing at all) seems bizarre. If I could find a Wagner 224 - like the one which still works well - I'd slot it in. But they are hard to source over here (and a quick check suggests that Rock Auto doesn't list the 224, which is also surprising).
 
Hm, well that eliminates the "previous owner goofiness" theory and validates that these are indeed the original units.

Thinking about it a bit more, it's probably still worth checking the grounds - remember that the turn signal only blinks one side of the vehicle, while the hazard circuit has to blink both sides, so that probably means that the 224 flasher there is rated to a higher current capacity since it's driving twice as many bulbs at one time. With a wonky ground, maybe the turn signal circuit is pulling more current than is normal, enough to make the 552 act up but still within the tolerances of the 224.

Even though all the bulbs are working, it's probably worth checking all the grounds anyway, as well as pulling each bulb on these circuits and checking the socket contacts for oxidation/corrosion.

Since you're running a 93, you have the old-style sockets like my 92 has, and if you've got any rust issues in the rear quarter panels, then there's a better-than-even chance that those sockets are corroding, since the connection points where the wires enter the sockets aren't weather-shielded.

With my truck, I did have corrosion issues on those sockets due to rust issues in the rear quarter panels, so I know they can get bad. I never saw erratic operation like you're describing, but I did have sockets fail completely or rust up so bad I couldn't get a bulb out, so your symptoms don't seem unreasonable for corroded sockets.

If your tail light sockets are bad, an alternative to direct replacement is grafting the 97-01 style sockets onto your harnesses like I just did. The brake/tail and turn sockets will slot right into our tail lights, but the reverse socket doesn't due to it being two-tab (and ours are three-tab). The newer sockets are weather sealed, and are "lower profile" since the later models don't have the cutouts our sockets sit into, so it makes fitting our lights back onto the body easier too once you figure out how to rotate each of the three into the right positions. For all six positions (brake/tail, turn, reverse on each light), you'll need 3 harnesses. If you use the 4th position for rear fogs, then a 4th will be needed. I converted a 3rd brake/tail socket to two-wire by tying the "minor" wire (tail filament) to ground - the two-wire sockets are just 3-wire ones with only the "major" (brake) and ground populated.

The other gotcha is the gaskets - the later ones have a rubber/silicone one, and it's not thick enough for our housings. That's easily solved, though, by reusing the foam seals from the older sockets, either on top of the rubber ones or in place (whichever gives a snug fit and still permits you to rotate into a "locked" position.

Still it's not a bad job to do if you've got any experience with wiring and take your time to be sure you don't mix up the brake and tail wires.

Oh, and if you do this then you only need one bulb type for all the converted positions - simpler for carrying spares.
 
Rob - that's a really coherent and persuasive diagnosis. The point about circuits pulling more current than normal because of dodgy connections seems credible. Since swapping around the relays hasn't solved the problem but just revealed some possible clues, clearly it makes sense to check out all the bulbs, sockets and light fittings.

I changed/replaced both front turn bulbs some years ago as the originals were white and I had to put orange ones in to make it legal for UK. I've had the little front corner ones in and out several times in recent months when doing other stuff. I haven't opened up and looked at the rear light units in years, if ever.

I'll work my way round all four corners of the vehicle with some electro-contact spray in hand, and see what all the connections and wiring look like. More info to follow when I've done that over the weekend....
 
Sounds good. Hopefully this will turn up something that points at a cause.
 
Well here's an update - and the mystery is still not solved!

I've been round all six of the bulb-connections. The two front corner ones inside the orange plastic reflectors are clean and sound. The front flashers (which in my Jeep are re-wired into what was originally the white sidelight units below the headlamps, and now have orange bulbs in them) are also fine - but I gave them a squirt of electro-contact spray anyway.

The rear lamp assemblies were dusty inside, but the body-panels are not at all rusty, there's no worn or damaged wiring-insulation and all the rubber seals are good. I took out and checked the turn-indicator bulbs. One had a little bit of rust around the bulb-base and the socket, so I cleaned it all off nice and shiny and then gave both a spray.

So.... I reckon the wiring circuits, ground-connections and bulbs are as sound as they can be.

After all that I tried the turn-indicators and the hazards again. The problem remains. The blue Wagner 224 flasher relay, originally for the hazard circuit, operates the hazards fine; and when swapped into the turn-indicator circuit, works the turn signals equally well. But none of the other three flasher relays I now have (the original Wagner 552 turn-flasher, the unbranded aluminium universal replacement, and the 'heavy duty' one) works properly in either circuit. Either nothing happens, or the lights flash erratically - either staying on, not illuminating, or flashing sporadically. Seems very weird.

If I could get hold of another blue Wagner 224 relay I'd put that in, so that both circuits were using that particular unit. But it does seem hard to find.

The only other point (which may be obvious...) is that there is clearly a link between the two circuits, because if either flasher unit is removed, the other circuit doesn't function at all. I am also beginning to wonder if there might be a bad connection or a short somewhere at the back of the fuse mounting board - because "wiggling" the relays in their sockets does seem to affect whether they operate or not. Sometimes they click, even though the lights don't flash. It's not easy to remove that fuseblock to look at the wiring behind it...

Electrical problems, especially when intermittent, do seem hard to diagnose!
 
I'd ohm test the ground part of the bulb sockets to a known good ground. The only way to know a good known ground is an ohm test to battery neutral.
Check the voltage at the bulb center contact to a known good ground.

There may be resistance in the power side lowering the voltage/amperage below tolerable levels.

Even with good voltage to the bulb socket, there can be excessive resistance.

The way the nonelectronic modules work is a bimetal, they are thermal flashers. Old technology, a copper/steel piece of metal heats up breaks contact. cools makes contact again and repeat. The module is roughly tuned to the watt (volts X amps = watts) usage/flow. The bimetal does fatigue and wears out on occasion. But the most common problems are a mismatch of the flasher and the watt usage/flow, either because of the grounds, voltage/amp supply or bulb mismatch (either the number of bulbs, burnt out bulb or the bulb watt rating).

You really have to ohm test the ground circuits, many places for this system to go wrong.

If you don't already have one, add a ground from the battery negative to the inside fender well, this is a partial workaround for some of the ground troublespots. Can't really hurt anything, but may help.

I've actually had the best luck with a universal flasher designed for trailer usage (6 bulb). I don't know exactly why but they seem to work.

Just a couple of WAGS (wild assed guesses) have you done any dash work lately, is the ground to the lower left dash knee panel mount connected (forgotten ?). Turn signal contacts under the steering wheel crispy? The front clip lighting harness connector behind the airbox severely corroded? If you have a stick shift and clutch, is the clutch cylinder leaking brake fluid onto the fuse block? Check the wiring near the headlight buckets for cutting or rub-throughs. Double check the splices, you mentioned some running light turn signal mods.

I've had some serious issues troubleshooting the lighting on XJ's, time intensive and many not so obvious problems can crop up.
 
Thanks 8Mud for that detailed advice. I'll dig out a meter and do what I can to test ground connections and voltages in the way you suggest.

Just to respond on the other points....

I don't at present have an extra ground connection (or as we call it, an "earth strap") from battery negative to chassis. I did fit one such strap on another car I have, for much the same reason, so I may try it.

I haven't done any dash work. I confess I don't know exactly where "....the ground connection to lower left dash knee panel mount..." might be, but certainly haven't removed or disconnected anything that might fit such a description! Might need a pic or diagram to identify it.

Turn signal contacts and switch on steering column seem OK. Wiring and connections around the headlights and airbox also seem OK but I can't say 100%. My XJ is auto, so no stick shift or clutch to leak fluid.

The mod to the lighting wiring was to have the original sidelights converted to orange turn-indicators. The sidelight wiring now feeds a small bulb within the replacement headlight units - which are replacements because although it's an LHD vehicle I have to have left-dipping headlamps to be legal in UK. Fortunately Hella makes headlamps which have both the main/dip headlight bulbs and the sidelight bulbs within the same unit....

Anyway, I'll check the splices as best I can (don't want to undo all the carefully-reconfigured knitting and risk creating more problems).

The only other possible clue - which might be totally irrelevant, but might equally be a key piece of evidence - relates to the point about dash work. My speedometer needle behaves erratically too. This pre-dates the turn/hazard modules misbehaviour by about a year. The odometer works fine and clocks up the mileage accurately. But the speedo needle has a mind of its own: sometimes takes 15 minutes/several miles to wake up, sometimes rotates anticlockwise, sometimes reads a consistent 20mph more than the actual speed, sometimes works perfectly. I wonder - is this another symptom of a bad electrical or ground connection somewhere behind the dash?
 
I'm still having problems troubleshooting this (not least because I'm no expert at using ohmmeter/voltage-meter).

The bulb-sockets all seem fine - I think. I have tried to test the hazard flasher unit socket in the fusebox. I assumed one terminal-socket would be live when the hazard switch was on, and the other was a ground. But the live one only has power when the ignition is on (though the hazards should surely function even with ignition off?).

I'm wondering whether there is a bad ground somewhere. But exactly where and how do I check them? I cannot see how to get behind the fusebox in the footwell to check the contacts there.

I have the workshop manual wiring diagram, which lists no less than 11 ground-connections to the chassis. But it doesn't show exactly where these grounds are located on the vehicle.

I can see most of the ones in the engine bay. But ... where exactly are the grounds on the "left side shield" and "left side cowl", "left side cover" and "right side kick panel"? Crucially, which ground(s) serve the lighting and turn indicator circuits? Can anyone point me in the direction of a diagram or set of photos which actually shows where to find the various ground-to-chassis contacts?
 
Well, time for an update, and it seems the problem is (almost) solved.

Long story short, it turns out that it was the blue plastic Wagner 224 that was faulty. With all the swapping over of the two flasher units (blue Wagner 224 and silver Wagner 552) to see what worked and what didn't, I was - for a while - confused as to which socket in the fuse panel was for the turn-circuit and which for the hazards.

Anyhow, I now have good flasher-units in both sockets, and the turn indicators and hazards work as they should.

Meanwhile with the help of advice from cruiser54 I checked and cleaned up most of the ground connections (which were actually not corroded). The one that is hard to reach is below the steering wheel, under the dash, so that remains to be checked.....

The faulty speedo needle seems to be an unrelated problem: I think the speedo on my '93 XJ is electronic, not driven by a mechanical cable, but I have no clue how to make it work normally..
 
Glad to hear you got the blinkers working right.

As to the speedo, it should be electronic - the thing on the tcase that has the little gear on my '92 just has an electrical connection on it, so odds are yours should be the same. The fact that the odometer is working properly leads me to believe you're getting a good signal from that and it's getting to the cluster OK.

I don't know the innards of the cluster/speedo, so I'm not sure if the cluster circuit board is providing two copies of the signal into the speedo/odo unit (one for odo, one for needle) or just one and it's being split internally, but if you have access to the factory wiring schematics for your truck it might show something. I can try to remember to check in the factory service manual for my '92 over the weekend, as far as I know 91-95 models used the same cluster so it may be applicable.
 
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