Turn Signal Flasher Relay

Just trying to diagnose an issue: Turn signal arrows do not light up on Instrument Cluster

When using turn signal right or left, I can hear clicking from relay, and the actual outside lights flash correctly.
Hazards work too. The hazards idiot blinks on the instrument cluster.
The fuse that controls turn signals and brake lights look good, and brake lights work.
I’ve pulled and tested instrument cluster, and applying 12V to the correct plug contacts light up the turn signal lights.
BUT the flasher relay is making a slow sick sound though when turn signals are clicking.
OH, and when car is first started, I know it’s usual for the battery light to stay on a few seconds. If I have the turn signals on too, the battery light will flash!

Can the relay correctly work for the outside lights and hazards, but not the instrument cluster direction arrows?

DAC1731 is the relay. Common fault?

Common fault. That’s the turn signal bulb failure indication.

so that means an outside turn signal light IS out? Rear lights blink, front lights in bumper blink. Are the side lights near front fenders supposed to blink too?

Not necessarily. It could also mean that one or more of the outside turn signal bulbs have been replaced with an incorrect spec bulb that doesn’t pull enough current.

I suppose it could also mean that the bulb failure feature of your turn signal relay is malfunctioning.

Open question: Could it be because your system voltage is low, or there’s a poor connection somewhere so the turn signals aren’t seeing full 12V? I dunno. Your description of the symptoms sounds like low voltage might be an issue, and Jaguar wiring is notorious for high resistance crimped connections 30 years on.

Hmmm, OK. I’ll do some investigating. I haven’t owned car long enough to remember if the side lights flash or not with the turn signals. I’ll check those bulbs.

Voltage has been good, AFAIK. Battery is always charged, gauge indicates 13-14V when running.

I should also pull the turn signal relay and check it for corrosion I guess. Turn signals have been working fine up until now.

And tonight I’m going to replace ALL my fuses. Since I’ve owned the car, I keep getting periodic fuse blows, and it’s always an original fuse from 1988.

Mine did the same thing until I replaced the bulb in the right rear blinker. It worked fine but wasn’t actually the right spec bulb. Put the right spec in and then it flashed inside when just using the signal!

Side lights definitely do not blink in my '89.

Ironically, I had the exact problem this week with my 85 XJ6. The outside blinkers all worked perfectly, but the indicators inside would not light up. There was no voltage to the bulbs inside the tach or speedometer. Long story short, it was the turn signal relay. The relay would click normally but wasn’t sending current to the bulbs. I had an extra on the shelf. Once replacing the relay, the bulbs blinked perfectly.

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Found the relay, very easy.

Mine also ticks slow, then fast, then slow. That doesn’t sound right to me…Have ordered new one for $17…it’s worth a try.

Follow up. Replaced turn signal relay, now arrows on instrument cluster are blinking. :slight_smile:

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I know this is an old thread, but saves starting a new one for a similar problem. 1988 xj12 indicators just stopped working (also the hazards) with no warning, like a blown fuse, no power. Fuses were ok so I went a purchased a new relay flasher unit. Now the strange part. All indicators on the outside of the car now work, as they did before. But the indicators on the dashboard only light up for the first flash and then stay unlit but the indicators still continue to flash normally on the outside of the car. Any ideas?

Hi Brett and welcome.

Did you get the correct relay?
Or it could be that the replacement relay has also a problem?

Is it just my eyes, or does the the drawing look mixed up?

Looks like the speedo and tach don’t know their left from their right, Jerry.

Jim, maybe that is the source of confusion for these alien turn signal indicator sightings?

Well Jerry, over the years i have decided that many many people don’t use them either because they are afraid of using up the battery ; or they might not know where to replenish the blinker fluid. But you have opened my eyes…they are Aliens!

IF … I am recalling correctly from my old electronics days (that was 50 years ago … if not, I will be corrected :smile: ).

Based on the drawing Aristides provided (see my corrections for the L and R indicator mix up), I also added the circuit path from IGN (+12V) to ground (-12V), the following is the wiring:

Upper left corner, from IGN switch, through NC contact on hazard switch, +12V goes to flasher terminal 49, which apparently is the +12V feed to the turn signal circuit in the flasher, and feeds the turn signal switch through terminal 49a.

The turn signal switch feeds +12V to the outside lamps, which have their other side connected to ground to complete their circuits.

IGN +12V goes to the indicator lights in the tach and the speedo, with the other side of the indicator lights going through diode and connecting to the +12V from the turn signal switch to the outside turn lamps. The diodes only allow current flow in one direction, so the indicator lamps are only ON when the outside lamps are OFF. The diodes don’t allow current flow through the indicator lamps when the flasher IGN +12V is OFF to the indicator lights (+12V is ON through the turn signal switch to the outside lamps).

If the diodes are bad (allow current to flow in both directions, then the indicator lamps will light under both conditions (when IGN +12V is to the indicator lights and when +12V from the turn signal switch is to the outside lamps).

First, use an ohm meter to check the diodes with the meter’s (typical) 1.5V battery. You should read continuity through the diodes in one direction, but not when you switch the meter leads to test with the polarity reversed.

IF that is good, then do this check at 12V (diodes might be good at 1.5V, but shorting out at 12V): put +12V to one side of the diode and -12V to the other contact of the light, then switch the polarity of the 12V.

The indicator lights should be ON when +12V is applied to the side of the indicator light not connected to the diode, but should NOT be ON when the +12V is connected to the diode connected to the light and -12V connected to the other side of the light.

I didn’t double check, I just handed the old relay over the counter and asked for a new one. That may be an error on my part and will check that when it warms up a bit more later today. The first step and the easiest.
Edit, I have a same year xj40, will check what relay is on that car and see if its the same and give it a try.
Edit No 2. Here are a couple of pics from the faulty relay, Im guessing that it is the correct one for that car ?
Here is the link (and screenshot) of the replacement one they gave me. Its a Tridon FET16

Pics of original faulty relay flasher

I don’t really understand the markings on them so I don’t know if I was given the correct relay / flasher

the schematic supplied above is slightly different to the 88 XJS V12 which i have, i can post an extract of it here in full colour if you want, the info on the bottom of the flasher is>> #31 = earth, 49 = light green/ pink stripe - to - hazard warning switch, #49 a (alt/c) = light green/blue trace to turn signal switch

Im guessing its the new relay thats the issue. In the forums I just came across this post from Ron_Knipper.
"A few years ago, I did an LED conversion and made a little project of analyzing the DAC1731 (Hella TBB44) flasher. I posted on the subject.

Not all 4-pin flashers are functionally equivalent. The XJ/XJS requires that the 4th C-pin operate as a pilot circuit for the dash indicators. The typical auto parts store 4-pin flasher has a C2-pin for trailers etc and will hyperflash in a Jag. There are a handful of aftermarket flashers that are compatible with the DAC1731. I tested the Lucas, Rover, and Flosser devices; although I did not have a Uro device for testing, it would be shocking if it were incompatible (I use a lot of Uro parts). BTW none of these flashers are LED compatible."