Author Topic: C4 Instrument Display.  (Read 4592 times)

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Offline Vettech

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C4 Instrument Display.
« on: May 27, 2017, 07:44:08 PM »
Coming home the other week, I noticed my display backlights went off (now cant see LCD display) also R & L indicators and the blue Highbeam  indicator are on.
Checked all fuzes - AOK. Studied the cct diagram, concluded I had lost an Earth. Lost it between G201 - S213 - and D1, the main connector on the back of the Cluster.

Since this car is converted I decided cluster connector which has been modified (butchered) would be a good start, but alas I found earth right thru and onto D1. The trouble is the cable/connectors are so short, its a PITA to work on.

Has any C4 owner had a similar fault, or, if you have an Elect Service Supplement, you may see something Ive missed. Any info appreciated.
Vettech.

Offline gtc

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Re: C4 Instrument Display.
« Reply #1 on: May 28, 2017, 02:05:44 AM »
Sounds like a call for Sirfixalot!
It's C3 chromie for me, see? Si!

Offline Bfit

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Re: C4 Instrument Display.
« Reply #2 on: May 28, 2017, 05:56:36 AM »
I think these have a auto dimming system,  photo cell in the cluster.
Bfit
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Offline Vettech

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Re: C4 Instrument Display.
« Reply #3 on: May 28, 2017, 09:57:15 AM »
Sirfixalot is enjoying Regensberg.
Yes they have a sensor to dim lights.
This does not explain the two blinkers and blue high beam indicator being solid on, when they should be off.
I'll have to re-remove cluster, and strip and seperate the two PCB's, maybe the "D1 earth pin" is cracked on the unseen side, these are double sided PCB's.

With a new day maybe there is still some one out there who knows this fault.
Vettech.

Offline Vettech

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Re: C4 Instrument Display.
« Reply #4 on: May 28, 2017, 03:24:13 PM »
Well Bfit, I looked at your idea, not much info in the Elect Supplement so i got out "The Service Manual", 4 1/2 x4 fold out A4 sheets double sided with circirts gallor, but nill relating to anything inside the Cluster. Took out top PCB, there is what looks like a power supply, but at a guess its the dimmer come intensity circuit as it has the LDR or light sensor connected to it and a leg of the 3Pin Reg connected to the Halogen backlight cct. I'd guess a LM317 Adj Voltage Regulator.
So I removed the four Halogens, put cluster back in car, now the R&L blinkers and the High beam are not lit.
Indicates to me that the "Dimmer cct" is shot, giving a earthy short on the cct causing the Indicators to glow.

Now for some investigation, as the Reg has "(M)713  1301K" on it - I assume "Motorola" but you know what happens when we assume!........

Now might be time to look for a download I had from a Mr Killybrew - I think, which was on Clusters.
Vettech.

Offline Vettech

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Re: C4 Instrument Display.
« Reply #5 on: July 19, 2017, 03:26:43 PM »
After some time and tooing and frowing, I emailed BATEE.COM in the states (good site by the way for C4 cluster info also Porche) purchased several repair kits and a test lead set up, these arrived today - and so will begin a new round of work.
Vettech.

Offline Vettech

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Re: C4 Instrument Display.
« Reply #6 on: July 23, 2017, 03:50:39 PM »
Well at last I have removed and re-installed all parts, switched it on - NOTHING not even the original fault.
Depression sets in.

But one good thing, the test lead set allows me to light it up, on the bench. And upon closer inspection the display is alive.

Re inspect, now a new fault, created when the 12pin plug is resoldered, the upper PCB tracks have not taken, gave it a good dose of heat & solder
but to be on the safe side used some jumper wire to hard wire the pin to the copper track. This is a problem with double sided PCB's.

Screwed it all back together, then one last bench test, bloody hell, not working again, what now.
Crack in C9 pin on the 32pin connector, this is the I/O connector which is butchered and turned 90 upon conversion.
First place to look for faults, as the soldering is a nightmare. Now all working.

Had enough, roast garlic/rosemary lamb is smelling good - I'll put it back in the car tomorrow.
Vettech.

Offline Vettech

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Re: C4 Instrument Display.
« Reply #7 on: July 23, 2017, 07:37:52 PM »
Oh! And I may have inadvertantly fixed another little problem.

The dash Voltmeter always reads 0.6V lower than the battery.

Today on my last bench test it read 12.4V and when I checked the power supply with a good Fluke Digital MM it read 12.4V.
So maybe this issue has been resolved, unless there is 0.6V loss in the car wiring. Tomorrow will tell.

Feeling not so depressed now.
Vettech.

Offline Vettech

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Re: C4 Instrument Display.
« Reply #8 on: July 28, 2017, 02:00:15 PM »
Ok. All back in.

All working, this little exercise highlights the hidden issues with double sided PCB's.
I do have several pics of the issues but I cant put on here. I have these on my Pad at the monthly meeting if any one has Questions

The Voltmetre reads the correct car battery\alternator output. [a bonus]

Went down Hoxton Pk aerodrome, accelerates like all $#$, lights up Bobs Tyres like magic.

The day looks sunnier already.

Vettech.

Offline MY081

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Re: C4 Instrument Display.
« Reply #9 on: July 28, 2017, 04:49:56 PM »
Ok how do I get onto Hoxton Park Air Strip

Offline Bfit

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Re: C4 Instrument Display.
« Reply #10 on: July 28, 2017, 05:57:33 PM »
Wire cutters at dusk
Someone to claim us, someone to follow
Someone to shame us, some brave Apollo
Someone to fool us, someone like you
We want you, Big Brother
Big Brother!

Offline Vettech

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  • The rocket sled in Steel Blue.
  • Location: Cecil Hills. N S W.
  • Mood: Electrofied.
  • Car: C3 78 + C4 87 + C4 90
Re: C4 Instrument Display.
« Reply #11 on: July 28, 2017, 06:29:01 PM »
1. The airport has actually gone.
2. Northward up Cowpasture, under M7, then immediate left at the lights.
3. The road into what was Masters - slight bend then 600 or 700m of straight,
4. No ins or outs, maybe a few B-doubles parked on the northern side only.

Slight dip in the far end is causing my new wheel/tyre to rub something. No not that.

NOW! Just when I thought it was fixed, its got another fault. The auto dimming is not working.
The manual dimming (turn light switch when headlights on) is working ok.
This is a pain because I changed these parts - just in case.
Back to the circuit.
Vettech.