DOOR KEY LAMP

Post by **Philippe** » Fri Apr 30, 2021 7:48 pm

Hey guys, I need some help. I have a 1995 Ford Probe 2.5 V6 Second generation. When I bought the car, the driver's side door key lamp didn't work. Recently I attempted to replace the bulb but it still doesn't work and now the passenger side bulb and ignition lamp won't work either. I have checked all the fuses in both engine and interior- all ok. Checked microswitches in both handles- all ok. I'm wondering if it might be the CPU/fuse box. Any thoughts would be greatly appreciated. Thank you

Post by **Kit** » Sat May 01, 2021 7:18 am

I’ll send you. CPU to try if you , if you like

£15 posted this inc a ‘Forum Members’ surcharge
Reduced to £5 posted, if you take up ‘Full Membership’

Kit

Post by **Philippe** » Sat May 01, 2021 6:10 pm

Thanks Kit. I'm going to check the CPU is working first and get back to you if thats ok.

Post by **Philippe** » Thu May 06, 2021 6:47 pm

I think the CPU might be ok. I used an LED bulb on the driver's side but the passenger side is a standard bulb. I didn't replace it because it was working so I'm going to order a standard bulb for the drivers side, around 4mm 12W 0.092amp and see if that works. If anyone can recommend a company I can buy one from, please let me know as I'm struggling a bit on that front. Everything seems to be LED these days.

Post by **Kit** » Thu May 06, 2021 7:13 pm

Maplin was a source, but their shops are now closed
Do they still sell 'on Line’

Kit

Post by **Philippe** » Mon May 24, 2021 12:23 am

Hi, Sorry for the delay, been a bit busy now we are officially out of lockdown. Thank you for the suggestion, I did find some bulbs on eBay in the end.

Just to update everyone on what I have done so far.

This is a picture of the driver's side (right hand drive) before I started

This is a picture of the driver's side after I replaced the bulb

This is a picture of the new bulb and harness I fitted into the car.
I put a harness to make it easier to refit as its connected directly to the original harness lightbulb/outside handle microswitch, by fitting a harness, I can remove it without dismantling the door handle.

I replaced both the driver's side and passenger side bulbs (not the ignition key bulb as that was working before) however, now all 3 do not work.

I have checked the lightbulbs and car handle microswitch with voltmeter, also checked wires and fuses. All seems to be in working order.

The only thing I can think of, is that its the CPU that is no longer working. It is the original one after all. I looked at the CPU condition (please see picture below) but I'm not sure what to look for. Someone mentioned capacitors.

Does anyone know how you can tell if the CPU is at fault?

This is a picture of CPU

I have also added the specs of the light bulb I fitted incase anyone is interested in replacing them.

Any help would be greatly appreciated. Thank you

Post by **Micron** » Mon May 24, 2021 9:21 am

Are you getting any voltage to the switch, assuming it's using the car body for the return? Are the earths good?
Can you trace the voltage from it's source?

I can't look at present and can't until at least Wednesday, but I do have wiring diagrams if it helps. However someone might have access to the diagrams sooner.

Post by **Haulin** » Mon May 24, 2021 6:28 pm

Check voltage from the ignition key lamp connector. When my CPU was bad, the ground pin had also some sort of voltage. Also I may remember wrong, but ain't the door key lamps 6 volt ones? Atleast I remember replacing them once with 12v leds, but once I connected the other side, both "died". Disconnected the other lamp and the other one started working again.

Post by **Philippe** » Wed May 26, 2021 9:02 pm

Thank you for the replies.
Next week I will try to trace the voltage. Yes a wiring diagram might definitely help to pin point exactly where the bulb wire goes.
As for the CPU, there are quite a lot of pins, do I check any specific pin? How do you test it?
The specs for the bulb are from the Mazda RX-7
I thought all lightbulbs in a car where 12v?
I connected the old bulb I originally removed to a 12v battery and it was working.
If I put a 6v bulb on a 12v battery, I assume it would pop and burn out right?

Post by **Haulin** » Thu May 27, 2021 4:07 pm

So I did remember wrong.. it's been years since I battled with this same problem. Yeah 6v bulb pops on 12v battery. I tried to diagnose the CPU, but couldn't make any sense of it. But if the ignition key lamp connector has some weird voltage readings, it's 100% faulty CPU. The + pin should have constant 12v and ground pin grounds whenever the door is open or when you pull outside door handle (micro switch). With my faulty CPU, the ground was something like 9v with door open and 2v door closed.

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