Ke55 cluster not working properly

[79rolla]

Hey guys and girls, I have some questions for you all. So i have a 79 ke55 and I am having a few troubles with it. The temp gauge doesn't work when connected, the fuel gauge has stopped working now after a while of working on and off. As well as the speedo doesnt work properly. What I mean by the speedo not working properly is that at 60 it says 60 by the speedo, but at 100 the speedo reads at 120. As well as the blue sheet on the back of the cluster doesn't like being tightened properly (doesnt let gauges work when tight) at what I believe is the regulator for the fuel and temp gauges. What could be the causes for this? Why is the speedo out? Why is the fuel gauge not working? Hope this makes sense for everyone to read. 

 

Cheers 79rolla 

[altezzaclub]

Pull it out...  A painful job,but you'll need it on the bench unless you can measure the voltage at the gauges by lying under the dash.

This is a KE70 cluster diagram, I don't know how different it is.

..and the whole diagram for a KE70.  There must be KE55 wiring diagrams somewhere on the net, but most web pages saying they have diagrams are pretty dodgy for some reason.

The answer may be in here-

https://www.youtube.com/watch?v=BI0R9KrMyqg

Good luck- If you get stuck PM Banjo, he has one and he is the electrical guru around here.

 

[79rolla]

Thanks altezzaclub.

I will have a bit of a sus and see. It could be the voltage reg but not 100% sure. I know that is a common fail point. 

 

Cheers 79rolla 

[Banjo]

The voltage regulator, will fix at least half your issues. The reason there is a voltage regulator, is that you don't want guages like fuel & temperature etc. tied to the +12V battery terminal voltage; which can vary a lot from cranking (7v-8V), to full on output of the alternator, whilst charging (14V - 15V).

The voltage regulator for the gauge/s, is chosen as well below +12V. They are commonly 6V, 7V, or 8V.  One real crude regulator I have here was a vibrating contact on the rear of the fuel gauge, & created an average voltage that was lower than the supply voltage of +12 volts. 

I even found one, that used a 10V regulator.

 

The ones in the dash area, are usually nestled in between the various dash light bulbs; & often burn out, as they don't like things like fuel gage going short circuit to ground.  Taking the dashboard out is a horrible job; (especially if You have big hands), but will be necessary if you are to fix or replace the regulator, If your dash wiring is printed circuit type, You will often find the voltage printed on the printed circuit plastic arrangement, adjacent to the regulator, which will often be "charred". I have repaired them in the past, with a standard LM7806 or LM7808 voltage regulator, available from places like Jaycar Electronics, & the like.  When You get your dash out of the car; turn it over &, & take a picture of it, & post it here, & we'll see how bad it is, & suggest how it can be possibly be repaired.

P.S.  I do remember having the same issue as You; a long time ago, & modifying the dash panel as I mentioned above. It's been running for probably a decade, & I never had another issue.  Maybe, I posted about it here somewhere ?  I'll take a look.

LINK:   2017    https://www.rollaclub.com/board/topic/73224-that-pesky-little-guage-voltage-regulator/#comment-708505

Cheers Banjo

 

 

Edited May 26 by Banjo

[79rolla]

This is what the back of my cluster looks like. 1 other question for you banjo, would you know why it only sometimes gets power?

Cheers 79rolla 

 

[79rolla]

Umm so i'm getting -61ohms at the cluster. Yes I'm using a cheap multimeter but -61 doesnt seme right. What should it be at? 100? The tank is probably about half to 3 quarters full.

Also the gauge only moves with a ground wire straight to sender.

Cheers 79rolla 

Edited Monday at 07:56 AM by 79rolla

[Banjo]

Good Morning !  Your picture indicates that the regulator in your particular dash unit, is a +10 volt model.  The circuit for your fuel guage is very, very simple.  When You turn on the ignition, the car batteries +12V is fed to the voltage regulator, which converts its output voltage to +10 volts. The reason there is a lower voltage, so that the fuel gauge's accuracy, is not affected by the +12V supply bouncing around, as it does. The first thing You should be measuring is not the resistance of the sender unit, in the fuel tank; but whether You have +10V at the so detailed terminal, on the back of the dash assembly. As I noted previously; it is the voltage regulators that are prone to fail, in these dashes. Turn the ignition on, & using your multimeter on a DC voltage range higher than 10 volts, measure the voltage between the terminal marked 10V, & chassis ground.  There is a good chance the regulator has failed; & as result the fuel gauge will not read; even if it's resistance varies over the correct range. If you Google this subject, you'll find a number of articles & videos, regarding this issue.  Here is one that may assist You.

https://www.youtube.com/watch?v=Z7iRxnILM3U&t=28s

I trust that assists.

Cheers Banjo

Edited Tuesday at 12:03 AM by Banjo

[79rolla]

So i have the 10v at where is shows that it should on the cluster. At this point I'm going through ground wires, but not 100% sure where they all are and if that may be the problem.

 

Cheers 79rolla 

[79rolla]

So I'm getting 9v at the wire for the sender. Is that right? Thats at the fuel tank itself. Or do I have other problems?

Cheers 79rolla 

[Banjo]

OK, If you are measuring +9V at the fuel tank, that is a good start. However, if the regulator is marked as being a +10V one; then the +9V reading, is a bit low. That could be your multimeter. Check it by starting your engine, & putting the multimeter DC volts  leads across the car battery. If the battery is fully charged, & your alternator & regulator is working correctly, the voltage should read somewhere between 12v to 14.5V.

If the reading of the battery voltage was OK, then we can assume the multimeter, is reading reasonably accurate.   When you got a reading in the boot, on the wire from the dash; was the wire measured connected to the fuel level sender, or not ?  If it was connected to the fuel level sender; did the fuel guage display any defection at all, of the indicating needle ?  I would suggest that You fill up your tank to full, so you know what the level actually is, that the guage is suppose to be indicating. That's because it is a "bugger" of a job, to remove the tank, to extract the sender unit; so that you should make that your last resort, in trouble shooting. If your fuel guage is displaying some level, irrespective of whether it is correct, then it indicates there is no open circuit in the wiring.  The level sensors, in the tank, do however, have a habit of wearing out after many years of use. If you get the +9V voltage at the disconnected wire in the boot, then that indicates, that possibly the fuel guage is in bad shape, & that maybe the +10V regulator has an issue. I would suggest, disconnecting the fuel sender wire, in the boot, above the tank; then measure the +10V terminal on the back of the dashboard. If is still reading +9V with no load, then the voltage regulator has an issue, as is most common.  I might add, that while you are doing these tests, that you disconnect the coolant temperature sensor, near the bottom of the top water hose, in case it has an issue, & is loading up the +10V regulator.  Sorry I cannot be any more specific, as there are a few variables in there. 

Basically disconnect the fuel guage & sendor, & the coolant temp sensor initially, & check whether that +9v reading, remains the same, or changes in some way.  That may give me an idea, as to what is going on there.

P.S.  Unfortunately, that circuit that Altezzaclub posted does not indicate a +7 to +10V regulator at all. It depicts all the guages being connected to +12V battery supply, which is a bit strange.  Maybe it's a very early circuit. However, your photo of the rear of your dashboard; indicates it should have a +10v regulator therein. 

Cheers Banjo

 

Edited yesterday at 12:24 AM by Banjo

[79rolla]

Yeah mate. I know that my alternator isnt good as it charges at 16v at the moment

 

Cheers 79rolla 

[Banjo]

Quote

"my alternator isnt good as it charges at 16v at the moment"

That is not good. Assuming your battery is fully charged, it might be a good idea, to disconnect the alternator, whilst trying to sort out this fuel & temp guage issues.

Cheers Banjo

[79rolla]

Battery went flat yesterday with key on but I will mate.

 

Cheers 79rolla 

[79rolla]

Hey mate so it wasnt connected to the sender when I measured it.  But Just checked now and still no change in it working. Car is about 1/2 full at the moment. And the temp sender is disconnected and has been for a while. But with the fuel sender wire not connected it only reads the 9v other wise with connected only 5v. So I'm going to try the reg but ill see how it goes and update you later..

 

Cheers 79rolla 

[79rolla]

With the battery connected and car running it charging at 13.8v with both terminals off battery while running its about 16v. If i can't fix it soon I'm going to just get an after market one and find a place to mount it. 

 

Cheers 79rolla 

Edited 18 hours ago by 79rolla