2002 CL733 with what i believe to be incorrect gauge readings

[cl733]

I noticed awhile back that i had a voltmeter gauge with a reading of about 10.5-11 volts , I had my alternator rebuilt recently so I thought maybe the alternator was the fault. I took it off and had it checked, but it was all good. So i just bought a new gauge to put in , and it also always hovers in about the same range, hardly ever reaching over 12 volts, a check with a volt meter on the CB power posts shows there to be 12.3 + volts when the volt meter in the dash reads in the 11 range.

The second thing going on is that my water temp and oil temp gauges are reading higher than they normally do also. My fan only kicks in when the needle is starting into the red. I have always noticed before the fan kicking in when the needle was around an 1/8- 3/16 past the 180 degree mark. I also have replaced both thermostats within the last year, so I'm not believing they are sticking (it's an ISX 565  ). Am planning on replacing them with the ones I had originally taken out just to be sure. It isn't a thermostat issue, when the gauge is showing in the red, the bottom out let on the rad is easily touched by my hand. I've also added a much bigger core count rad along time ago and this truck has an enormous cooling capacity,

With a new fan stat sending unit it still does the same thing, Im not believing the gauges , would the lower voltage present at the dash could that be doing something to how the gauge reads,    as soon as i can im going to pull the gauge pod and check incoming voltage  to see if it actually is low   and check  the wiring contacts to be sure ive not got a bad contact anywhere 

     Any input greatly appreciated       

                            Thanks Don

[abmac]

I believe you have the wires mixed up. If you wire the temperature gauge from the coolant level you can get higher reading.The same with the voltmeter

[br549]

Ck  and clean the ground from the engine, alternator to frame.  What year model is this.  Does you have the two 12 post junction box on the drivers side firewall?  I have seen a lot of gauges be off when the ground wire on the bottom terminal is loose, that is the ground wire to cab. clean good and trace the wire back to frame and clean too. Sometimes I would run a new short wire between the inside and outside junction strip at the bottom.   Usually when these wires are loose when you mash the clutch pedal in and out you can see the gauges move a little bit.  This sounds like a ground problem.

[br549]

Just seen the year model,  You might not have that setup.  I might have the ground relay on front of cab, still ck all the grame to cab grounds.  there is additional ground wire in the glove box on passenger side. Would't think that many gauges would have corrosion on the plug in pins in the dash but did have one where the voltmeter gauge was reading low and pull the gauge and sand paper the terminals and put back in and corrected the problem.  Is this the new style dash or the old flat style dash.

[turckster]

You should check voltage at the alternator and compare it to voltages at the starter, cab and batteries. There should not be more than .5 volt variance. There is a ground relay next to the wiper motor, make sure the contacts are clean.  I would make sure all cable connections are clean, including grounds on the block and frame. 

The alternator should be putting out approx.  14.1 volts, voltage inside the cab should be around 13.8 volts or so.  

[cl733]

Ok now ill tell you the rest of the story    and what i did to fix it

So im starting into a long weekend and know im not going to have much time to be finding parts  so while im at the alternator rebuilder  , he tells me to try re energize the alternator   almost for sure it will pick up the voltage, so i pick up a new regulator   figuring if the re energize  doesnt work then i got plan b, 

Re energized   and still no difference    put in the new regulator    no difference,    panic sets in, as i cant have this thing shutting down on me with a load of asphalt on,   so my last   bit of time before everything is shut down for the weekend i go out and buy a new alternator and am confident my problems are over

  new alternator installed   and guess what  same condition,  so im thinking    wtf     got to be the batteries    yank all the batteries out for a fluid level check  and a good cleaning ,  load testing them with a 100 amp load shows them to hold it pretty good   but the voltage seems low   so i throw them on a charger

  left charging while i replaced some o-rings in my fan hub   like all day     these are 13 month old exide 925 cca batteries

   they all charged up until they kicked out the charger    and i checked them for voltage again  the charger says the batteries are at 60%   so im thinking again   wtf     i reach for the hydrometer and check all these 4 batteries and find 1 cell out of the whole works barely floats in the white and all the rest are in the top of the  red

   So now im on the hunt for 4 batteries    where i bought them only offers a 12 month warranty from purchase time   even though exide offers a 18 month replacement   so no warranty   guess ill deal somewhere else  then   and i pick up 4 1000 cca   and plug them back in figuring problem solved 

     Wrong     new alternator    new batteries    same problem     and its late monday  and i work in the morning      so now really   wtf

    So there is something simple wrong here all 3 main cab chassis, frame  grounds are cleaned up   so i just grab a set of jumper cables  and run from pos on alternator to pos battery   no change     go from negative on alt to neg battery  and shazam   volt meter picks up to 14v   and everything seems perfect 

    So i follow the alt ground    it crosses over to the night switch (i believe   hard to see but looks most probable)  the night switch switches off the grounds all the batt grounds one the one side , and neg grounds to starter,    so i just added a new ground for now from the alt to battery ground  that pretty much by passes the night switch now

  Been nearly a month now and its perfect , volt meter sits on 14 - 14.1   my temp gauge and oil temp gauge  dropped down to its normal operating range    when i have free time ill jump across the night switch and remove my new ground to be sure of my assumptions   

  Im thinking   when i put in those batteries 14 months ago   it was because i had one battery short out    and maybe it helped fry out the night switch, or maybe when i was trying to jump it with my diesel pick up , and burning a post off the battery  and taking out the alternator in it too   because of the short, why the night switch is failing

   I dont know    but i do know the alt to batt ground added fixed everything up    how it kept going that long   who knows   had to be doing some kind of charging 

   Thanks everyone for the replies  

[gearhead204]

Damn disconnect switches! ......have had several throw me a curve over the years. would make continuity, but no real amp flow without causing problems or what I call "slow voltage" all gauges read right touch the key and thunk  every thing goes dead then slowly goes back to normal. 

 

 

          How's things in the upper end of the valley? 2/3 thru apple harvest on this end.