75 Sedan: Plate-lights, no voltage in the 2 black and red wires ?

[anderfa]

"11v is a low reading which might be affecting the bulb warning system. What does your meter read when placed across the battery terminals?"

-On batteri-terminals, 12.6V on bulb-cables ca 11.6V , so drops ca 1V through thin cables etc, I think.


I really don`t understand this, and my time is running out !
I will try to change some old bulbs in the rear lights to new ones, in case some are almost gone or something like that.

[SD1too]

Originally Posted by anderfa

... BUT warning-light / broken bulb still shows on dashboard ?

I've consulted RAVE Anders which says that the bulb fault will be displayed when both lamps are faulty. Since you have demonstrated that your bulbs are illuminating correctly, the problem must lie elsewhere.

The bulb fault indication will show for the wing mounted direction indicator repeaters, the front fog lamps and the high level brake lamp even when those circuits are switched off (so says RAVE). You could check those.

The bulb fault warning for the number plate lamps should be displayed only when they are switched on and both lamps are open circuit or there is a fault in the circuit that mimics a high resistance or the bulbs are a non-standard type (you've said halogen which I assume is a mistake).

I hope this helps.

Simon

[suzublu]

Originally Posted by SD1too

I've consulted RAVE Anders which says that the bulb fault will be displayed when both lamps are faulty. Since you have demonstrated that your bulbs are illuminating correctly, the problem must lie elsewhere.



The bulb fault indication will show for the wing mounted direction indicator repeaters, the front fog lamps and the high level brake lamp even when those circuits are switched off (so says RAVE). You could check those.



The bulb fault warning for the number plate lamps should be displayed only when they are switched on and both lamps are open circuit or there is a fault in the circuit that mimics a high resistance or the bulbs are a non-standard type (you've said halogen which I assume is a mistake).



I hope this helps.



Simon

Simon, it's my observation that side repeaters aren't on the canbus system as I have leds in there, and piggy backed from them to leds in my mirrors 😉

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[SD1too]

Originally Posted by suzublu

Simon, it's my observation that side repeaters aren't on the canbus system ...

Hi Ron,

None of the exterior lighting is supplied by a bus. Each lamp unit is individually hard wired from the LSM.

The CANbus is a fast network used only for ABS, traction control, the instrument pack and the Automatic Transmission ECU. The network for body related equipment is the K-bus and the LSM is connected to that network but it doesn't use it to supply the bulbs. RAVE explains that they are fed by MOSFET transistors and the LSM monitors the current passing through them. If it changes abnormally, the bulb failure warning is generated and sent via the K-bus to the message centre.

Simon

[suzublu]

Originally Posted by SD1too

Hi Ron,

None of the exterior lighting is supplied by a bus. Each lamp unit is individually hard wired from the LSM.

The CANbus is a fast network used only for ABS, traction control, the instrument pack and the Automatic Transmission ECU. The network for body related equipment is the K-bus and the LSM is connected to that network but it doesn't use it to supply the bulbs. RAVE explains that they are fed by MOSFET transistors and the LSM monitors the current passing through them. If it changes abnormally, the bulb failure warning is generated and sent via the K-bus to the message centre.

Simon

If there was a thanks button Simon, I may have clicked it 😁 thanks 😎

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[anderfa]

I opened up one of the plate-lights, to doublecheck.
Looks like it has been hot in there, and the bulb I soldered in is a 10W instead of 5W as it should be.

This fault might be the answer ? if both are 10W, then it could be read like a faulty bulb ?

[SD1too]

Originally Posted by anderfa

This fault might be the answer ? if both are 10W, then it could be read like a faulty bulb ?

A 10 watt bulb will draw twice the current which will certainly appear abnormal to the LSM. The signs of heat you mention may also have caused damage to the conducting tracks.

Simon

[anderfa]

Update:
Only one of the 2 bulbs was 10W. Changed it to 5W, but warning on dash still on.

[SD1too]

Does your car have a message centre Anders, or just a generic bulb failure warning lamp?

The sidelights need to be switched on for each test but you probably already know that.

I'd say that the next step is to by-pass the printed circuit board by running test leads from the connectors directly to the lamp terminals.

Simon

[anderfa]

Thank you guys, for still being with me on this issue :-)


-I have just a bulb failure lamp showing on dashboard.

"The sidelights need to be switched on for each test but you probably already know that."
Are you thinking about the twist-button beside steeringwheel, where you can choose from straight up, parking light, and lights on (this will turn on lights in the AC-display and in dashboard etc.

If so, I have tried both straight up, and lights on , on the button, no difference on the warning light.

"I'd say that the next step is to by-pass the printed circuit board by running test leads from the connectors directly to the lamp terminals."
I have already run extra cables bypassing circiut board about 2-3 years ago, and worked fine. This time around the black ground cable with plug, did not show voltage, so I solved that with running a new cable from the ground-bolt in the booth, then lights in bulbs.