shootnstarz

This is perplexing. 2001 auto coupe LF blinker doesn't work, RF does. Does not work with blinker or hazard. Very fast L t/s but the L hazard tail light was normal speed as is both R blinkers.

I have tested everything up front, am getting good voltage at the front wiring harness plug but will not light the LF turn signal bulb. Even direct wiring the plug to the socket doesn't do it while it does on the RF. It shows the same voltage on the L and the R prongs at the plug.

Just as I was doing more test with the hazards flashing they quit completely, no hazard warning lights at all. Still have normal R t/s and fast L.

I searched the forum and read something about problems with hazard flashers or maybe it was the hazard switch, couldn't really get a solid answer. Any input on why the LF won't light when the voltage at the plug is the same as the R's?

Rick

El original

Not to sound silly but did you try another (fresh) bulb in socket?

jcgunn

With OEM bulbs, the sockets get brittle/melted from the heat. I had to replace both on my 03 when I went with LED switchbacks.

shootnstarz

Yes, I have the lenses out and the headlight covers off so I have good access to the wiring. I have brand new lenses, sockets and bulbs and have tested everything with a jump starter. I tested the continuity in the lt blue/white wire from the female plug in the front wiring harness to the socket, no issue. I was able to light the LF t/s using it's own wire from the plug to the socket by directly connecting it to the jump starter.


I hooked 16 ga speaker wire from the LF and the ground prongs in the male plug and got nothing, moved to the right prong and it lit.

So I can only conclude the problem is upstream from the front harness plug and the hazards stopping during the test makes me wonder if they have anything to do with it. Strange that the male harness plug shows proper voltage but won't even lite the bulb wired directly.

shootnstarz

2001 auto coupe

GCG

It seems there is a bad contact upstream of the male plug that's causing the voltage to drop when the bulb's load is applied to the circuit. You can confirm this by keeping a voltmeter connected while you plug and unplug the bulb.

UM Rebel

Try to check resistance on Lt Blu/Wht wire back to fuse box. It should be very low (near zero). See attached wiring diagram. I'm thinking that wire may be pinched or nearly broken. Would be interested in what you find out to be the problem. Good luck!

GCG

In our cars the turn signal and hazard functions are provided by the hazard switch. There is also another important component in this mix that is known to develop bad contacts and affect the turn signals: the multifunction switch.

As I mentioned in my previous post, it seems you have a drop of voltage when the bulb in the FL t/s loads the circuit and that's typical of a bad contact. Since you only have problems on one side, it should not be the hazard switch, otherwise you would be having problems on both sides. That makes the multifunction switch the "better" candidate.

Now you are saying that the hazards are completely gone as well and that is throwing another layer of complication here.

There is a thread documenting how to disassemble the multifunction switch and clean its contacts. You may want to take a look at that.

shootnstarz

OK friends and neighbors, big update. After nearly 4 days and 3 different people working on it, nearly completely disassembling the steering column and dash, testing wire after wire the problem was narrowed down to...................................... .the left daytime running light relay.

After switching them back and forth and having no luck we pulled the relays and tested them. They tested fine. We continued testing things for another hour swapping the relays back and forth with no conclusions on the problem.

So as the guy was wrapping up his tools to leave I went ahead and stuck the bulbs back in their sockets and surprise surprise surprise, with the hazards still on the LF started working, something it had never done. The relays were installed in opposite slots from which they were originally.

So, 2 new $18 DRL relays and I now have 4, count'um, 4, working turn signals. I am happy. I can only assume testing the relays did something to make the LF start working.

I went ahead and replaced the hazard switch too, but it wasn't the problem. The inop hazards previously mentioned was a blown fuse.

I originally was looking for a turn signal relay but they don't exist in a C5, everything runs through the DRL relay.

Rick