2001 RX300 rear indicator fault - anyone else had this issue?

[Yoda400]

Hi everyone

A friend of mine has an 2001 RX300 and it has developed an odd fault with the rear indicators. Neither operate via the stalk. The fronts/sides rapidly blink when operating the stalk indicating one is out, but the bulbs are fine (tried new ones to be sure) and the relay is fine too (swapped with a known good one). Again on the hazards the fronts/sides are fine, just the rears don't illuminate 😞

Just a bit odd that it's both rears, and it's not the bulbs or relay. A dodgy joint earth somewhere perhaps? Anyone else had the issue?

Any suggestions would be very gratefully received (including where to look) - we are going to have a poke about on Sunday morning, so any knowledge would be great!

 

Thanks in advance

 

Yoda400

[Lager shandy]

Multi meter time check bulb holders and work your way back to the nearest plug first.

[Yoda400]

Sorry I thought i'd replied to this but the message mustn't have been sent, doh! I don't think it's bulb holders as they are fine, no corrosion plus they are making perfect contact with the bulbs.It's both sides too which have gone at the same time, so must be a fault elsewhere...Will dig out multimeter as you suggest, cheers

[PUKU]

I assume the bulbs are 'normal' indicator bulbs. If you replace with LED type that can throw all sorts of problems due to their very low current use. You do need basic filament lamps.

[Herbie]

40 minutes ago, PUKU said:

I assume the bulbs are 'normal' indicator bulbs. If you replace with LED type that can throw all sorts of problems due to their very low current use. You do need basic filament lamps.

LEDs are fine as indicator bulbs as long as you wire in a loading resistor (6Ω 10W if I remember correctly but may be wrong).

[Delphius1]

If the rear indicators are not lighting up but the front ones are, as others have said make sure the bulbs have continuity across the filament and make sure they are filament bulbs and not LEDs (which are polarity sensitive so only work in one position and need load resistors to work correctly).

If you are sure the bulbs have good filaments and the connectors are making good contact and they are still not working, check for 12v at the indicator socket when you switch the indicators on. Obviously one side at a time and you should see the 12v pulsing on and off in time to the rhythm of the other bulbs.

If you don't get 12v at the socket, then trace back the wiring.

I'd suspect the bulb failure module that monitors bulb failure of all the rear lights. All the light circuits go through that failure module and it's not unknown for the module to go open circuit and not supply voltage to the bulbs, especially if there has been water ingress and it's got into the module. It's a lottery if it goes open circuit if it illuminates the bulb failure light in the dial cluster.

Unfortunately I don't know the location of the bulb failure module, but I'm sure someone will come along with the info. :-)

The one on my old Supra went open circuit on the brake lights, so I had no brake lights and no indication on the dash that they had failed. Luckily a friend told me they weren't working when I pulled into a car park in front of him. Luckily he wasn't close enough to rear-end the car! In the end I just linked across the input and output for the brake lights and bypassed the bulb failure module.

[PUKU]

One other thought …. do you tow? is the relay and control wiring OK for the trailer socket?

[D_P]

Hi Yoda400, 

Did you solve the issue? I have a very similar problem, my rear right indicator doesn't work for turn or hazard, left and fronts are fine. On right turn signal, front starts flashing quickly, so initially thought it was the bulb. Bulb is fine, multimeter gives low reading and swapped left and right, left always works, right never works with whatever combination of bulbs. I also checked three fuses, no. 22 on fuse box B in the engine compartment, described as "Emergency Flashers", and nos. 5 and 21 in the fuse box under the glove compartment, described as  "Emergency flashers, navigation system, head up display" and "Position lights, tail lights, license plate lights, fog lights" respectively. All the fuses were fine. I can't find any others that could be related to the indicators.  

I also checked the voltage on the socket leads with the turn signal on right, and it was very low, around 0.1 V or thereabouts, but my multimeter is a digital one, and I'm not sure what the lag is in reading an on-off  pulse with a frequency of a 100 hz or so. 

I'm really stuck and would appreciate any hints. Does anybody know where this bulb fault module that Delphius mentions is? Does the the rear light loom lead back to some accessible socket?

Many thanks for reading!

 

[Herbie]

4 minutes ago, D_P said:

and I'm not sure what the lag is in reading an on-off  pulse with a frequency of a 100 hz or so. 

That's 100 flashes per second!

Have you checked the earths? Don't just pull at the wire and think it's tight enough, undo the nut and clean up all the connectors and earth points. It's dropping a lot of voltage somewhere so it's just a matter of finding where by tracing the wiring and cleaning all connectors.

[D_P]

Indeed, my mistake, i meant to say 100 flashes a mt, so more like 2 Hz. Is that light assembly easy to remove to clean around it? t's a rx450h. So far I only unscrewed the holder with a quarter turn and pulled it out. I will check the earth on it, good idea, I can check connectivity between each lead and the body.

[Herbie]

14 hours ago, D_P said:

Is that light assembly easy to remove to clean around it?

I honestly don't know as I've never needed to do it but I don't think you'll need to do that either. Just clean up the contacts in the bulb holder, clean and reseat the earths and if that hasn't cured the problem then it's multimeter out and fault-tracing time.