98 Polaris - temp sending gauge problem

[groomerdriver]

Years ago I installed a Polaris temp gauge to take the place of the idiot light on our 98 Polaris Classic. If memory serves, I didn't have to change the sensor that is in the block....but maybe I did...I don't remember.

What is happening now is that the gauge will move while it's warming up but once you give it some throttle the gauge needle drops back to the left just as if you disconnected the sensor from the gauge.

I have checked all connections and they are all fine. Could the sending unit be on it's way out? Or what else could I test/look for?

Thoughts?

 

[Builder Bob]

How about a few answers;
Are there any other electrical problems?
How does the electric start work?
How is the battery?
After the needle drops left, does it go hard left, to indicate that the engine is cold?
Is there anything you can do to cause the needle to indicate the correct engine temp?
Have you closely examined the wire from the sender to the gauge? Any worn spots?
How is the wire connection at the sender? Describe it?
I recall the Classic had an analog gas gauge, and Temp gauge.

 

[groomerdriver]

How about a few answers;
Are there any other electrical problems?
How does the electric start work?
How is the battery?
After the needle drops left, does it go hard left, to indicate that the engine is cold?
Is there anything you can do to cause the needle to indicate the correct engine temp?
Have you closely examined the wire from the sender to the gauge? Any worn spots?
How is the wire connection at the sender? Describe it?
I recall the Classic had an analog gas gauge, and Temp gauge.

No other problems

Estart works good

Battery new before this season

The needle starts in the middle of the "C" then falls ~1/8" to the left of the C. It never indicates engine temp at all. Nothing I do (wiggle wires, etc etc) seems to help.

This sled had the analog gas gauge and the idiot red temp light stock. I added the Polaris analog temp gauge shortly after we bought it used.....about 12 years ago.

Sending unit is brass colored that screws into the block just below the upper hose. It has a round male plug sticking out of it. The mating wire has a round female connector that snaps over the male plug.

Wires at the sending unit and gauge looked good. I did not check the entire length of the wire but will do that later today.

If I recall, the sending unit is just putting out X amount of current based on the temp of the coolant it is sensing. Is there a way to test the output with a multimeter?

Thanks Bob!

 

[jccams]

I believe the sending unit just varies the resistance based on water temp. Resistance changes as water temp changes. Should be able to unhook it and use the ohm setting on multimeter and see if it changes as water warms. I have no idea what the resistance should be, but there is probably a spec somewhere.

 

[groomerdriver]

I believe the sending unit just varies the resistance based on water temp. Resistance changes as water temp changes. Should be able to unhook it and use the ohm setting on multimeter and see if it changes as water warms. I have no idea what the resistance should be, but there is probably a spec somewhere.

Yes you are correct on what the sending unit does. I dug up my repair manual for the sled and while there is no test shown for an analog gauge, there is a test for the idiot light.

The sending unit seems to be operating properly based on the ohm readings while the sled was warming up then eventually cooling down.

I then really watched what the gauge was going while the sled was warming up and running on a stand. At idle (no throttle applied) the gauge seems to be working. As soon as you increase the engine RPM's the gauge needle indicator drops to below the "C" like a rock. Let off the throttle and it goes back to there it was.

I rewired the + and - wires by the gauge and no change. The wire from the sending unit to the gauge is OK.

Bad gauge?

 

[racerxnet]

Are you sure the regulators rectifier is not bleeding Ac into the harness?

MAK

 

[groomerdriver]

Are you sure the regulators rectifier is not bleeding Ac into the harness?

MAK

No I'm not. Can I check for this?

 

[jccams]

You could rule out the sending unit by watching the resistance when you increase throttle. If the gauge drops off like you say I would expect to see a drastic swing in resistance too. If resistance stays steady there is a issue with the voltage or the gauge. Put a volt meter on the wire harness unhooked from the gauge and see if the voltage changes drastically when you increase throttle.

 

[groomerdriver]

You could rule out the sending unit by watching the resistance when you increase throttle. If the gauge drops off like you say I would expect to see a drastic swing in resistance too. If resistance stays steady there is a issue with the voltage or the gauge. Put a volt meter on the wire harness unhooked from the gauge and see if the voltage changes drastically when you increase throttle.

There was no drastic change with RPM changes.

So which one could it be? The regulator or rectifier? This sled has both I believe and if memory serves, the regulator is right by the right footwell. I had to change this years ago after it failed after a period of time when I tried to wire all three lights ON at the same time. Obviously the regulator didn't like this after a month or so!

 

[jccams]

On an e-start sled the rectifier is part of the regulator, non e-start there is no rectifier, all AC. I am not sure if the gauge is powered with AC or DC, could be either. Like I said I'd put a voltmeter on the gauge wiring harness , or between any yellow and brown wires and look for voltage swings with throttle application. Regulators job is to keep a constant voltage if it varies much regulator is suspect.

 

[racerxnet]

Take the DVM (digital volt meter) and set it to AC and look at the output after connecting it to the gauge plug. You can read both AC and DC if present on the harness. No harm in selecting either with the meter. Get the schematic of the sled and look at the logic to determine how the gauge works.

Almost all non electric start sleds are 12 volts to the dash lights and tail lights. Looking at my manual for a non estart 1995 formula Z confirms this.



MAK

 

[groomerdriver]

This sled has both a separate rectifier and regulator. I tried to compress a PDF image of the wiring schematic for this sled but couldn't get it small enough.

Can I test each of them to see which one is working and which isn't?

 

[JimAndros]

Jim,

As I was reading this post, I was visualizing the regulator & rectifier being mounted together like you say. I think you have a bad T-stat and the RPM cause the coolant to circulate and drop in temp. I believe you are chasing a non-existent electrical problem.

Jim

 

[groomerdriver]

Jim,

As I was reading this post, I was visualizing the regulator & rectifier being mounted together like you say. I think you have a bad T-stat and the RPM cause the coolant to circulate and drop in temp. I believe you are chasing a non-existent electrical problem.

Jim

No I didn't say they were mounted together....they are in 2 different spots. I do not believe this sled has a tstat.

 

[jccams]

Jim,

As I was reading this post, I was visualizing the regulator & rectifier being mounted together like you say. I think you have a bad T-stat and the RPM cause the coolant to circulate and drop in temp. I believe you are chasing a non-existent electrical problem.

Jim

That is what I was originally thinking but this was dismissed when the resistance didn't vary with RPM increase. If the water was dropping temp the change in resistance would have confirmed this.

I guess I am not familiar with this vintage Polaris sled, my 2004 has a combined regulator and rectifier. I would think if the regulator was bad you would have blown your lights by now. Does it have an electric fuel gauge and if so is it functioning properly?

 

[groomerdriver]

That is what I was originally thinking but this was dismissed when the resistance didn't vary with RPM increase. If the water was dropping temp the change in resistance would have confirmed this.

I guess I am not familiar with this vintage Polaris sled, my 2004 has a combined regulator and rectifier. I would think if the regulator was bad you would have blown your lights by now. Does it have an electric fuel gauge and if so is it functioning properly?

Yes it has an electric fuel level gauge and it's working fine. All of the lighting are acting like a typical Polaris 2S. A bit dim until the engine is revved up.

Is there a way to check the rectifier and regulator for proper operation? Just want to cover all the bases.

 

[jccams]

Check regulator by putting volt meter across output, should measure about 12VAC and should remain pretty constant with RPM increase. Check rectifier by putting volt meter across output, should measure about 12VDC and remain pretty constant with RPM increase. Set meter to VAC to check regulator and VDC to check rectifier. Hope this helps.

 

[groomerdriver]

Check regulator by putting volt meter across output, should measure about 12VAC and should remain pretty constant with RPM increase. Check rectifier by putting volt meter across output, should measure about 12VDC and remain pretty constant with RPM increase. Set meter to VAC to check regulator and VDC to check rectifier. Hope this helps.

Yes it does....thanks!

 

[groomerdriver]

Check regulator by putting volt meter across output, should measure about 12VAC and should remain pretty constant with RPM increase. Check rectifier by putting volt meter across output, should measure about 12VDC and remain pretty constant with RPM increase. Set meter to VAC to check regulator and VDC to check rectifier. Hope this helps.

Both regulator and rectifier check out good per your instructions above.

I have removed the gauge holder and have it pushed out of the dash for easy access to the other wires. Pink - brown (or yellow...will edit once I'm sure) - black going to the gauge as well as yellow and brown for the light.

Can I check the pink-black-yellow/brown wires for ''something" and how do I check it?

 

[groomerdriver]

I THINK the sending unit is bad and here's why:

The Polaris gauge kit came with a separate wire to run from the sending unit to the gauge. The factory idiot light wire that is in the sled harness was simply disconned on both ends. I plugged the idiot light wire into both the sending unit and the gauge and the gauge still didn't work right.......rev the motor and the gauge needle just drops off full to the LH side.

I checked the sending unit again with an ohm meter and when you rev the engine the ohm readout goes crazy.

So...using different wires...the gauge acts the same + ohm readout on the sending unit goes crazy when the engine is revved = bad sending unit

Any thoughts out there before I spend $50 on a sending unit?