Dash Instrument Lights LED conversion and FEM bypass - 2002 Thunderbird

[Frank Dreano]

Well, I found out my instrument cluster had been "hot wired" to make the lights burn full bright anytime the key was on - apparently to get around the typical FEM failure where the dash lights (and shifter light) go dark.
So I had to open up my instrument cluster to "unfornicate" the Bubba fix and remove a jumper and repair two cut wires and while I was in there- all 7 white gauge lamps and the 18 warning/status lights. Since the dash wiring was back to stock the lights wouldn't light as the FEM PWM output signal failed...

I wired a reversing relay off the middle DS tail light socket wire behind the trunk panel to send 12V to the front of the car when the wire's voltage goes low (e.g. lights on)...that wire acts as a trigger to an I put in the lower right side push-pin hole in the steering column cover (very unobtrusive). This arrangement makes sure the cluster lights only operate when the parking lights or headlights are on...

The dimmer switch has one wire that goes to ground and the dimmer PWM signal is wired behind the center stack to the high side of the shifter console indicator light (now also an LED); this is a BLACK wire in a 2002 and the ground is a WHITE wire (go figure). That shifter light wire "back feeds" the instrument cluster gauges on the same line that the FEM would normally use.

If I ever get the FEM fixed (prob not) all I have to do is unplug the trigger wire at the added dimmer switch and everything is back to stock function (except the LEDs). These are 60,000 hour LEDS so I doubt I'll ever pull the cluster again.

This video is the result and I dim and raise the light brightness towards the end. And I don't have to worry about that PITA FEM -- ever. My smartphone camera made the warning lights appear glaring for some reason; they really aren't bad, just brighter.

https://youtu.be/3Q0vmGemELA



Modified_Cluster_2.jpgLED_bulbs.PNGLED_Dimmer.PNG

[Frank Dreano]

This involved determining the "negative" contact on the instrument cluster for each bulb (the LEDs are polarity sensitive) those are indicated by the red dots in the first attachment and what the colors should be for the warning status bulbs; second attachment. The third attachment is where I placed the aftermarket dimmer switch .

Cluster_LEDs_marked.jpgICM_Face_Bulb_Colors.jpgIMG_1993.jpg

[RBIRD]

Interesting repair work-around. The trouble with an FEM problem is that most likely more issues will develop within it. Hoping for the best for you!

RBIRD

[Frank Dreano]

Yeah, the FEM can cause power steering and other lighting issues....but my research shows the frontrunner problem with the FEM is the dash/shifter light issue, by a pretty wide margin. It must be a weak area in the design of the component...

[HKS]

Frank,
I appreciate your sharing the experience and technical knowledge on this dash light conversion project..
I enjoyed reading about this. I no longer have the time to attempt the LED conversion. I have to be satisfied with wishful thinking.

Thanks very much.

Hermann

[Frank Dreano]

Noooooo problem.

[engine103]

Way above me. Sent the cluster out to be repaired when turn signals and hazards went haywire( cluster problem diagnosed by ford), cluster repair guy said problem was poor quality build, good thing is I installed myself which saved a lot of money.

[HKS]

Yeah, the FEM can cause power steering and other lighting issues....but my research shows the frontrunner problem with the FEM is the dash/shifter light issue, by a pretty wide margin. It must be a weak area in the design of the component...

Frank,
There is an empty socket wired in parallel next to the transistor that takes care of the power steering. At one time Ford thought two MOSFETs in parallel would be better than one.
I am not sure if the lighting MOSFET also has an empty socket for a parallel second MOSFET.
These two circuits use pulse-width modulation to make LEDs linear and to control the power steering actuator. PW modulation generates more heat and that shortens the life of power components.
Hermann

P.S. There is a good reason why one transistor may be better than two. MOSFET high input capacitance. Double input capacitance equals slower switching, equals more heat generated for an almost non existent heatsink.

[Frank Dreano]

The instrument cluster removal is just nuts and bolts once you get the plastic trim panels out of the way - that's the nerve-wracking part to me; crack one of those or bust off a mounting pin and you've got a problem..

As to the MOSFETs I suspect there are a few well-known, high failure components inside the FEMs that the techs can swiftly spot. That guy in Michigan fixing the FEMs for $208 (with free return shipping) isn't making any money if he spends hours wringing out an issue. If the complaint is instrument lights out or power steering he most likely knows EXACTLY what failed and its a quick fix and turnaround...

The incandescent bulbs in the dash gauges are also use PWM for dimming IIRC....apparently it reduces flicker at low voltages... Its passingly strange that a simple instrument lighting circuit is so over-engineered....

[HKS]

The instrument cluster removal is just nuts and bolts once you get the plastic trim panels out of the way - that's the nerve-wracking part to me; crack one of those or bust off a mounting pin and you've got a problem..

As to the MOSFETs I suspect there are a few well-known, high failure components inside the FEMs that the techs can swiftly spot. That guy in Michigan fixing the FEMs for $208 (with free return shipping) isn't making any money if he spends hours wringing out an issue. If the complaint is instrument lights out or power steering he most likely knows EXACTLY what failed and its a quick fix and turnaround...

The incandescent bulbs in the dash gauges are also use PWM for dimming IIRC....apparently it reduces flicker at low voltages... Its passingly strange that a simple instrument lighting circuit is so over-engineered....

Frank,
I had my FEM repaired by the same guy you mentioned. I hope the replacement transistor he put in is better than the original MOSFET's available when the circuit was designed in 2000. The guy is secretive and he does not tell you what parts were replaced or repaired.
Hermann

[Frank Dreano]

Frank,
I had my FEM repaired by the same guy you mentioned. I hope the replacement transistor he put in is better than the original MOSFET's available when the circuit was designed in 2000. The guy is secretive and he does not tell you what parts were replaced or repaired.
Hermann

Well I bought a used 2002 FEM and it fixed my dash/shifter light problem; I sent the original off to this gent for repair. I'm sure he knows exactly how to fix this common problem in 10 minutes with a soldering iron and 1 or 2 electrical components; prob under an hour (well under) for this issue and the charge is $208 -- not a bad gig...

[007Cruiser]

Yes. Knowledge is a wonderful thing.

[RBIRD]

I wonder what he would charge to change out all the mosfets to a new fresh set. Might save another hassle with the FEM?

[HKS]

I wonder what he would charge to change out all the mosfets to a new fresh set. Might save another hassle with the FEM?

When I had him repair the power steering MOSFET (Transistor) he asked me if I also had trouble with the instrument lights.
I hope he changed both the power steering and the lighting MOSFETs since he offers a 4 year guarantee. My instrument lights were OK.

So, my opinion is: Only the instrument panel MOSFET and the power steering actuator MOSFET are the ones that fail and need to be replaced.
The other ones should last 40 years unless they had a defect when installed the first time.
HKS

[Brian76rs]

This involved determining the "negative" contact on the instrument cluster for each bulb (the LEDs are polarity sensitive) those are indicated by the red dots in the first attachment and what the colors should be for the warning status bulbs; second attachment. The third attachment is where I placed the aftermarket dimmer switch .

Cluster_LEDs_marked.jpgICM_Face_Bulb_Colors.jpgIMG_1993.jpg

New here and just picked up an '02 with about 75k miles. Learning my way around all these common problem areas. That said, got a a "newsed" FEM module to take care of the speed sensitive steering issue - everything else worked fine. However, with the previously mentioned newly sourced FEM, the dash/shift lights do not come on. So, my question is - do I need to dig for someone potentially having gone through your above mentioned "Bubba Fix"? Curious if the bypass suddenly no longer works when a properly functioning FEM is in place - OR - is it that my new FEM has the light issue, but not steering...ugh.

Appreciate any help.

B