91 Testarossa turn signal inop

Sounds like your flasher module has failed. The module gets power either from fuse 24 (key power) or live battery power. Both can't have failed.

Looking at the wiring diagrams, both sources of power do seem to go through the Hazard Switch to the flasher module. I suppose if the plug has fallen off the switch, you won't get power to the module. How easy is it to access the back of the Hazard Switch?

Flasher module (USA) P/N 61651800

Image Unavailable, Please Login

 

How does the Hazard Switch action feel? In theory, if it was stuck between on and off, power wouldn't get to the flasher module (either for turn or hazard).

 

Strange. The wiring diagrams don't show a fuse (on the module). @Steve Magnusson

I don't know if it's to protect the internal circuits of the module or the external circuits. Would you have a better lit photo of the module/fuse and the wiring going to the holder?

Here's a wiring diagram for a USA Testarossa:

See component (27) on the left of the diagram.

https://www.dropbox.com/t/NVe03vNzUnjBeioO

Link expires in 6 days.

There should be a brown wire with (EDIT) key power on it going to the module (if the Hazard switch in the off position and is working properly). Is the fuse inline with the brown wire?

Live battery volts should be on the brown wire with the Hazard Switch pushed.

The Hazard switch is provided with 12 volts on a green wire from fuse 24 (when the Hazard switch is not pushed)

 

Don't know if you were directing this comment at me, but I agree -- never heard of a local 3A fuse at the TR Flasher (nor seen one on any TR schematic). I believe 3A would be too small to simultaneously flash all of the (incandescent) front and rear lights used in the hazard function.

 

Thanks, Steve.

@seanpatrick The Hazard system is provided with live battery power from fuse 4, but there would be a lot more things broken if that was blown. Headlight motors, parking lights and clock.

 

Interesting... Uses red wires. Are they spliced into the brown wire?

It may or may not be related to the hazard/turn system. Sometimes Ferrari attach unrelated fuses to module holders (I've seen that on the Ferrari 456)

 

If you can confirm the wiring setup of the fuse, that may be a possibility. I don't know the internal setup of the module and how it responds to external shorts. Maybe you could look at all the turn bulbs and holders to see if there are any short circuits first.

It may sound tedious, but it would probably be best to do so... unless Steve has any other suggestions.

 

Have to know how/where the fuse's wires are connected. (Even though it's mounted on the connector for the Flasher, I can't think of any reason why it would be associated with the Flasher function).

 

"first pic" is not a good description as the display of your photos on my computer may not match how they are displayed on yours. Can you add some sort of markings to your photos to show which are the red wires of the fuse?

Also, are you confirming that the red wires of the 3A fuse do not connect to any of the wires going to the Flasher?

And finally, if you replace the 3A fuse, do the turn signals work?

 

What is the "device in the first pic"? Something near the flasher unit? Is it shown in the graphic, maybe item 8, the tachometric speed relay?

Image Unavailable, Please Login
The speed relay has a red wire, but no fuse in the diagram I have. The tachometric speed relay appears to provide power to the coils of the fuel pump relays. I can't imagine the car would run if the fuse kept blowing.

(Sorry, cross-posted with Steve)

 

Does the car run at the moment? Does it run with the fuse removed?

Does the fuse holder look OEM? Is it an integral part of the flasher module socket?

 

@Steve Magnusson

Steve, that connector (?) in this photo...

Image Unavailable, Please Login

... has a green/black circumferally striped wire. Is this type of old fashioned striping associated with audio systems or something in particular on the TR?

 

The three wires in that connector certainly look like stock TR wires, but I don't recognize that connector (nor that combination of wire colors). Is the red fuse wire the only wire on the other side of that connector (and connected to the red wire) or are there additional wires connected to the other wires on the other side?

 

Does look completely unrelated to the Flasher operation (other than just being mounted to the Flasher connector).

 

Very unusual, and almost certainly is something that someone added IMO. So are the blue-black wire and the green-black wire connected together in the same terminal, or do they each have their own terminal (and are each connected to nothing)?