instrument cluster question

[bryonbush 85]

First time posting on this forum as I purchased my 69 convertible last month.

 

Here's where im at:

gas gauge wasn't working, but replaced the sending unit, now that's fixed.

turn signals, engine temp, and oil pressure gauges still don't work.

 

im thinking Sunday ill pull the dash off and see what we have for wire connections. I purchased the voltage regulator already but should I just go ahead and order the control board and replace that as well since ill have the dash off?

[Super Birthday Snake 11]

Welcome to my world, I can't get anything working. Have bought 2 new CVR's and 2 new Circuits and nothing, be interested to hear what you come up with.

[Pakrat 1,043]

Pulling the dash off is a pain and the circuit boards aren't that expensive so I would do it while you are in there. If it doesn't need replacing now it probably soon will.

 

Welcome BTW, always love to see another vert owner on the boards!

Edited June 5, 2014 by Pakrat

[miketyler 15]

If VR checks ok, I would pay special attention to the plug and possibly clean the copper contacts on it and PCB. I think you can check for incoming voltage to the VR at the plug as well.

Edited June 5, 2014 by miketyler

[bryonbush 85]

Super Birthday, its funny you say that because before i joined here, i was reading over your posts. Talked to a guy who had the same problem. He said he finally got sick of it enough to rewire each issues one at a time, from engine to dash. he said that was the only way he could get it to work right.

[danno 128]

You have a mystery. If you got your fuel guage to work, there is really no other single thing that could cause the other problems to occur. The common things are the 12 volts from the dash harness not making connection, the constant voltage unit not working, the ground not connected, and one of the guages shorted to ground (to the frame behind the nuts that mount it to the flexstrip).

 

Is your fuel guage reading the correct value? If you have a short in the sense line, it will look like it is reading a full tank, even though you could be empty.

 

Otherwise, you need to remove the instrument panel. I have gotten pretty good at it, after removing mine about 1000 times. The real trick is to reach behind it and release the speedometer cable. It is real simple if you know how, extremely difficult if you do not. If you do not know how to remove it, read about it or ask.

[Super Birthday Snake 11]

Super Birthday, its funny you say that because before i joined here, i was reading over your posts. Talked to a guy who had the same problem. He said he finally got sick of it enough to rewire each issues one at a time, from engine to dash. he said that was the only way he could get it to work right.

 

Really, half the problem is I don't know where to start. My dash is off so that's done and I think I've got one bulb working. I've heard a lot about new circuits being generally junk but I finding hard to believe they all are. I put my multimeter against each wire on the plug with the key on but no ignition and didn't get a reading off one of them which I presume to be very bad. So I guess my problem could be quite vast. Determined to sort it out though.

[LoneWolf2U 136]

If the gas guage reads, the reg is working.

Do a ground test on the oil/temp at the sending units to see if the guages respond before removing the dash.

By turn signals do not work? Dash lamps or ALL lamps fail to flash.

 

Snake, you cannot get a reading from the reg as power is pulsed at 6v, dig meters will not read fast enough to match pulse rate.

Check your dash ground conection, loose or missing will hamper other lamps and guages.

[Super Birthday Snake 11]

If the gas guage reads, the reg is working.

Do a ground test on the oil/temp at the sending units to see if the guages respond before removing the dash.

By turn signals do not work? Dash lamps or ALL lamps fail to flash.

 

Snake, you cannot get a reading from the reg as power is pulsed at 6v, dig meters will not read fast enough to match pulse rate.

Check your dash ground conection, loose or missing will hamper other lamps and guages.

 

Thanks will double check. The only dash ground I have is one wire coming off the plug and pretty sure that's all good but no harm in checking again.

 

Also good to know about the meter reading, learnt something else!

 

Sorry for the thread hijack/piggy back by the way!

[LoneWolf2U 136]

Also check your body to engine block strap connection, Alt to reg/block grounds.

I added a ground strap from the neg cable end to rad support for extra measure.

All guages and lamps work perfectly with no flicker or dimming.

[bryonbush 85]

the dash lights all work as well as the high beam indicator but the turn signal do not. gas gauge appears to be working correctly, but when we put the sending unit in, we filled it up right away when we shouldve checked it while it was empty and then filled up. but i does appear to be correct as the level is dropping ever so slightly as i drive.

 

Heres curve ball for ya... so the previous owner stated he couldnt ever get the gauges to work. but by the shape of the sending unit, i dont think he tried very hard to solve the problem. SOOOo i have three after-market gauges on the side that show the temp and oil pressure that work. what im wondering is if he took the wires from the dash, and re-routed them to the aftermarket ones for simplicity.:angry:

[Midlife 814]

the dash lights all work as well as the high beam indicator but the turn signal do not. gas gauge appears to be working correctly, but when we put the sending unit in, we filled it up right away when we shouldve checked it while it was empty and then filled up. but i does appear to be correct as the level is dropping ever so slightly as i drive.

 

Heres curve ball for ya... so the previous owner stated he couldnt ever get the gauges to work. but by the shape of the sending unit, i dont think he tried very hard to solve the problem. SOOOo i have three after-market gauges on the side that show the temp and oil pressure that work. what im wondering is if he took the wires from the dash, and re-routed them to the aftermarket ones for simplicity.:angry:

OMG...that's probably the issue. One cannot willy-nilly change incoming wires on the circuit card. You need to compare your dash cluster wire colors to what should be there. I can provide that info to you, but I would need to know if you have a factory tach dash or non-tach dash.

[miketyler 15]

I would have thought most guys that bought aftermarket gauges will run new wiring that came with the kit. Many times they bought a set of gauges because the existing ones didnt work or OEM wiring was a mess. The theory should be easy to prove by looking at the sending units under the hood and see what wires are run to them.

[bryonbush 85]

midlife: i have the non tac dash.

Miketyler: ill check the sending unit wires tomorrow and compare to the gauges on the floor and post back.

-today I went ahead and started replacing the dash bulbs with the LED light bulbs by reach from below. good news is that the right turn signal is working as well as the emergency brake light (which never did before) but now only the speedo side lights up. Im for sure going to be doing a while dash restore when its apart.

[Midlife 814]

Pin order for 69 non-tach dash:

Dash Cluster Pin 2 green/white

Dash Cluster Pin 4 red/white

Dash Cluster Pin 5 yellow/white

Dash Cluster pin 6 purple

Dash Cluster pin 7 red/yellow

Dash Cluster pin 8 black

Dash Cluster pin 11 black Violet

Dash Cluster pin 12 blue/red

Dash Cluster pin 13 white/blue

Dash Cluster pin 14 white/red

Dash Cluster pin 15 green/black

Dash Cluster pin 16 yellow

Dash Cluster pin 17 red

[bryonbush 85]

thanks midlife, saved that to my computer so hopefully when im home i can work on it. Found out from the previous owner that the new gauges he put didnt use any of the cords from behind the dash but used the ones they came with.

[SA69mach 39]

I have been watching this thread because I have been 'fixing' and faultfinding with the gauges/senders for a 70 and then a 69 I own.

some points to note that may help you

 

The reproduction IVR units are solid state and will show a constant 5.7 v, as opposed to the oem IVR units, which use a fast switching bi-metal internal and show a fluctuating signal. Your digital multi-meter should give you a solid 5.7 volt reading if you have an aftermarket IVR.

 

The reproduction circuit boards that I have purchased were both good out of the box.

 

Have a good look at the metal casing for your instruments. If flaky and rusty you may need to clean, smooth and repaint that. I cant say for sure, but I think it is possible to get a bad circuit if a sharp edge of rust pokes into the copper. (this is just my notion, and I have been wrong more often that right with these instruments)

 

I traced as many wires on the plug as I could, and had a chart for the plug in front of me when I did the rebuild and testing phase.

 

I would recommend setting up your board with some good alligator clips and a 12 v battery source, and thoroughly check all your bulbs and bulb holders. One by one, and check known 'good' bulbs and holders in holes that don't work. I found a lot of finicky faulty holders and bulbs. Some just are intermittent when pushed in, making things even harder to trace....

 

Gauges - wow, where to start. Ammeter is just a ampere indicator and a bit useless as a gauge. A voltmeter would be more useful, and I have been tempted to replace it.

Oil, fuel and temp all rely on senders and resistance to display a reading. Temp and fuel are EXACTLY the same gauge, just different printing on the face.

All three run the same resistance range - roughly 10 ohms "full" and 78-80 ohms "empty"

To truly test your gauges you need a potentiometer - a box with a adjustable dial which can produce exact resistance levels. You need to power up your gauges and feed them varying ohms to test accuracy according to factory limits (10 -78 ohms)

 

Grounding out the sending wires for gas, temp and oil should produce a fully pegged, or over-full reading. I did this will all my gauges and assumed the gauges were good. In hindsight I think that is a fault in the testing process with old gauges.

 

with all new senders and careful grounding and examination of the wiring, my temp and fuel gauges still showed faulty readings, (gas showed 2/3 when full, over half when Ir shows 185 degrees)

Now funny thing since the disappointment of the faulty gauges after rebuilding and replacing everything - I have noticed my gauges are staring to show much better accuracy, especially the gas gauge. it shows almost full when I fill it up now.

 

My new notion is that since the gauges were not used for so long, the needles and oil inside the actual gauges got gummy or stuck in a range limit. Now they are being used more, they are freeing up inside. this makes sense when you consider that most folks solve the issue of bad gauges by putting in new aftermarket Mustang gauges.

 

So, there is no magic fix for instruments and gauges. You must keep at it. I hope you do, and I wish you success. Both my cars are getting close to perfect gauges and instruments now. I put LED bulbs in both and that was a good move - much brighter.

[KipDurran 18]

My experience with the instrument cluster.

 

This started out with removing dash pad that I could repair the heater box. Then I did the usual cascade of events were I figure if on the to fix one thing I might as well fix another. I decided to upgrade to LED lights in the cluster. I also thought I would replace the printed circuit board so that in the future I will not have any problems with it. All of this went fine and then when I put it all back together I did not have the gas gauge, temp gauge or oil pressure gauge working.

 

I thought maybe it was the CVR. So I replaced this one with a solid-state one. Nothing. It was at this time that I noticed that some of my wires were melted. I sent the harness off to Midlife who kindly refurbished the harness for me (Thanks!).

 

I hooked everything back up and turn the key in anticipation. The gas gauge, temp gauge and will gauge still did not work. I took the cluster back out and I use my multimeter and I tested every connection that I could think of. The voltage in to the board was 12 V. The constant voltage regulator was 12 V and then 5 V out. When I put a 3 V battery on all of the instruments the needles moved. I put the old printed circuit back on. I tested the wire back to the tank sender and there was no resistance on the wire. The resistance at the fuel tank for the fuel gauge was in the mid 40s so I know that that was working. When I grounded out that wire however the fuel gauge needle did not move.

 

Finally I disassembled the complete gauge cluster and I took the fuel gauge and oil pressure gauge out just to look at them and make sure they looked okay and they did a didn't see anything wrong. I put them back.

 

Finally on about the fifth or sixth time of re-hooking everything back up the gauges started working. It is one of those things were I'm not exactly sure what I did but I am not going to question it at this point. I suspect that it was probably a grounding problem, gauge post touching the enclosure or a problem the the connection of the plug.

[SA69mach 39]

I also think the plug fitting is a bit suspect into the housing and most importantly, making good connection with the feed ribbons.

 

It is all just a bit fragile and many ways for a fault to happen, right there at the plug.

If I were smarter I would make up a interface that fits into the circuit board hole, and with some better connections into the plug. All connections marked for their function!!! That would allow easy testing of the cluster before installation, and eliminate the chance of poor connection to the plug.

All that fumbling and hoping at the back of the cluster would go away

[det0326 179]

I also think the plug fitting is a bit suspect into the housing and most importantly, making good connection with the feed ribbons.

 

It is all just a bit fragile and many ways for a fault to happen, right there at the plug.

If I were smarter I would make up a interface that fits into the circuit board hole, and with some better connections into the plug. All connections marked for their function!!! That would allow easy testing of the cluster before installation, and eliminate the chance of poor connection to the plug.

All that fumbling and hoping at the back of the cluster would go away

 

SA69mach

 

reading your post you are smart enough, make us a revision for our

instrument cluster. I have thought of doing this too actually hard wiring the cluster and put a heavy duty male and female plug of your choice.

 

Dave

[Super Birthday Snake 11]

Well after another few infuriating hours on this I'm not any further forward.

 

I checked for continuity on the gauges with the CVR unplugged to see if they were grounded but got no reading so seems fine.

 

I then checked the CVR voltage and got nothing off that either though, am I reading that right? I was just putting the red side of my voltmeter to the terminal on the CVR and grounding the black wire. Thought I should've got either 12v or 5.7v (it's a solid state). Also tried the red and black to the terminals directly on the CVR and got zip.

 

I checked my grounds and all seem ok, but why is there 2 ground wires coming from plug 4 on the instrument plug? Should one go somewhere else?

 

While I'm on the plug I've got the wires from the painless harness going to the instrument plug (tach dash). I've only got one wire, Voltmeter source and gauges B+ that I've got going to only one place on the plug. Looking at the diagram, I need this wire going to numbers 6,7,8 and 13 on the plug could that be the cause of all my problems? It seems so dumb that I'm going through this writing it out that I've missed this.

[det0326 179]

Super Birthday Snake

 

I am not familiar with your harness but one thing for sure if you are not getting voltage to the input side of your instrument voltage regulator then that is definitely one of your problems. You need to trace this feed back and see why you are not getting voltage to regulator.

Dave

Edited June 9, 2014 by det0326

[Midlife 814]

I checked my grounds and all seem ok, but why is there 2 ground wires coming from plug 4 on the instrument plug? Should one go somewhere else?

That's normal. There are three places for grounds: the clock circuit on the RH side, the dash cluster, and a ring connector near the headlight switch. Since the dash cluster is in the middle, the two other connectors are single wires, which join up at the dash cluster.

[Midlife 814]

I also think the plug fitting is a bit suspect into the housing and most importantly, making good connection with the feed ribbons.

 

It is all just a bit fragile and many ways for a fault to happen, right there at the plug.

If I were smarter I would make up a interface that fits into the circuit board hole, and with some better connections into the plug. All connections marked for their function!!! That would allow easy testing of the cluster before installation, and eliminate the chance of poor connection to the plug.

All that fumbling and hoping at the back of the cluster would go away

Right on! This design by Ford sucks big time. Those circuit card flap connectors are nearly next to worthless.

 

If someone wants to provide me an underdash harness and a dash cluster, I'll refurbish the harness and hard wire the cluster with a decent connector between the two, eliminating the circuit card. I need both to physically determine wire length runs from the cluster to the connector. Once I have this finished, I'll have a template that I can use in the future for converting clusters (eliminating the circuit card) to a sub-harness. I'd imagine the cost of converting an underdash and a cluster harness to be on the order of $50-$75, with reliability much higher than the circuit card provides.

 

Any takers on my offer of a free refurbishment?

[det0326 179]

Right on! This design by Ford sucks big time. Those circuit card flap connectors are nearly next to worthless.

 

If someone wants to provide me an underdash harness and a dash cluster, I'll refurbish the harness and hard wire the cluster with a decent connector between the two, eliminating the circuit card. I need both to physically determine wire length runs from the cluster to the connector. Once I have this finished, I'll have a template that I can use in the future for converting clusters (eliminating the circuit card) to a sub-harness. I'd imagine the cost of converting an underdash and a cluster harness to be on the order of $50-$75, with reliability much higher than the circuit card provides.

 

Any takers on my offer of a free refurbishment?

 

Yea I'm a taker I just talked to you the other day about refurbishing a harness. I have the instrument cluster and harness out of the car and won't really need it for maybe a couple of months.