Tachometer

The tach sender screws into the Bell housing, with the dozer NOT running,loosen lock nut screw in until it touchs,back off a half a turn and resecure.If that des not get it going again it could be a bad tach, bad sender, or wire

Tommy

Affordable Tractor Sales

“Your Jinma Parts Superstore”

http://www.affordabletractorsalesco.com

You'll need an oscilloscope to test the sender.  Most people who are not super cool don't have one handy .  I believe SOP for tachometer troubleshooting is first to adjust the sender as mentioned above.  Failing that, then it's a process of elimination.  Replace each piece one by one until it works.  

since dozers see a LOT of vibration you might check the connections.  Does the light work inside the tach?  If not, perhaps the first wire to check should be power.

My tach on my yuchai dozer won't work again.  I tried the sender on the bell housing by loosening it, tightening it, backing out 3/4 turn to no avail.  It seems like an electrical problem.  Everything else on the dash works, all dash lights work, front headlights and rear lights,the tach responds when I turn on the key but it won't respond and show RPM's once the engine is started.  I originally had this problem intermittently a few years ago and now it's back.  The dozer sits quite a bit and I only start it and move it every month or so.   It's going to be sold shortly and the tach definitely needs to work before it goes on craigslist.  Overall these dozers hold up pretty well.  I've had it for three years+. I've checked all connections under the dash and all tach wires are hooked up from what I can tell.

I put a multi-meter on the output signal from the two leads on the bell housing to no avail.  I put the multi-meter to AC and it showed zero volts.  Any recommendations or something else that could be the problem?  I do have access to an oscilloscope, but would prefer another route.  

Thanks

Brock

Did some more research tonight.

I think it might be the alternator =(

I started it up and then unplugged the negative battery cable.  All the lights went off.  put a DC meter on the output of the alternator = 0 volts

Is this something Keno tractor can replace?  What does Bob Rooks recommend?

I guess I should expect this when it sits so often.

Thanks

Brock

You won't get any output from the alternator with no field current going to it from the voltage regulator, that's why the battery must be connected to perform that test.

Just put the meter leads across the battery posts (pos to pos, neg to neg) and read the meter with the engine running about 1,200 r/m. You should be seeing 13.5+ volts DC.

You should make double sure all of the connections are clean and tight, including all of the grounds.

Bob,

I took a quick video w/ my phone of the behavior I am seeing.  I spoke to Mark at Keno today and he said there is a regulator under the dash that might be a problem  They go bad.  Also my indicator light won't come on when the dozer is running.  Here's the youtube link.  I have 12v when everything's off, and 13-14 when it's running.  

Mark at Keno said that I should order a regulator before an alternator. 

Link to youtube video –

http://youtu.be/LaR7AEdW3TM

Brock

Brock,

You say you got nothing at the tach sender.  That seems strange.   Of the ones I tested on Chinese tractors there was about .5 volts at idle and about 4 3/4 volts at full throttle.  The values are in AC  not DC. 

Brock,

From the video it acts like your reluctor (tach sending unit) is very dirty. Try removing and cleaning it.

Also, check all of the instrument ground and wiring connections.

Not sure how you have your ammeter connected, but the OEM alternator is only good for about 14 amps, on a good day. If you have 13 – 14 volts DC when it's running, you're okay.

The voltage regulator is mounted next to the fuse block under the hood, and it also has a red indicator light on it which shows field current going to the alternator which is illuminated when the key switch is on. Again, check all connections and if the indicator light doesn't come on, replace the regulator.

Either you are out of fuel or your fuel gauge doesn't work.

Your in-dash ammeter shows a slight discharge at higher engine speed. Correct? Another sign of voltage regulator (or meter) failure, or just bad connections.

The red indicator light on the dash mimics the indicator light on the voltage regulator, see if it's burned out.

Larry is correct on the reluctor values. AC not DC.

…red indicator light on it which shows field current going to the alternator which is illuminated when the key switch is on

The red indicator light on the dash mimics the indicator light on the voltage regulator

Ohhhh so THAT'S what the indicator light indicates!  Mine never indicated anything.

“Ohhhh so THAT'S what the indicator light indicates!  Mine never indicated anything.”

I think the real reason behind the light is to indicate that the key switch circuit is closed. Since these engines aren't equipped with shut down solenoids, it's a reminder that the switch is on.

“I think the real reason behind the light is to indicate that the key
switch circuit is closed. Since these engines aren't equipped with shut
down solenoids, it's a reminder that the switch is on.”

That's exactly right Bob.  It was very common on the tractors for people to leave the key on then come back to a dead battery at some future date.  Some tractors would count up hours on the meter because the key was on. 

Still don't have the tach working.  I hooked up my voltmeter to the output pins of the sender.  No voltage at all at idle.  I guess this means I don't need the oscilloscope to test.  In terms of removing the tach sender, do you simply loosen the two bolts by the sender to remove the entire unit?  or does the whole unit unscrew itself? 

Guess it's time to replace it.

Thanks

Brock

Brock,

It will be self evident. remove the two bolts and spin (unthread) the adapter plate off the sending unit. Assemble in reverse order.

It was the sender.  I ordered through keno and had to unfortunately get a new tach w/ it too, as they would not separate the order.  The sender + tach was about $60 bucks and took a week or two to get in the mail.  The original tach was fine.  I plugged it in, started up the dozer and we're in business.  The dozer is now for sale as I haven't needed it for about a year and a half.  It has just under 40 hours.  I'm in Northern CA and asking $9000.  it has shuttle-shift, rubber tracks, a 5' box scraper.  

Brock

530-680-6678 cell

Chico, CA

We have the senders as a seperate part ?

Tommy

Affordable Tractor Sales

“Your Jinma Parts Superstore”

http://www.affordabletractorsalesco.com