SEE bugs: Electrical: No power issue with fresh batteries

[MrSEE]

Hi guys,

Very strange issue I've been chasing for awhile now. I won't try to influence how you see it, but I will say I've tried about everything. Here are the symptoms and what I've done so far.

Machine starts very well and runs well. Voltmeter pegs under 24v before start and until running, where it stays around 25-26v while messing about

At lower temps (sub-20 degrees F?) it will not show power on the gauges or power up the starter.

Battery switch is good-- continuity test with cab off

batteries are brand new, but regardless provide 25.7v

Ignition switch is good-- I've replaced from a functional unit and tested/compared

Battery cables checked. Fine. Grounds good on frame behind battery box, but we cleaned and tightened those as well. Also checked and cleaned the positive cable and traced up to starter

5 24v relays all new on relay panel under headlight switch.

I clean nearly all contacts manually on these as a matter of procedure. Fuse panel has been cleaned/brushed and all new fuses

No chewed wires under dash and two under-dash/behind gauge grounds are clean and tight

Alternator has been tested and is excellent. Brushes full.

I've bypassed the DCE/IC shunt... tried with and without this in circuit.

I've replaced the 24v/50 amp fuse under the alternator from a functioning unit. No change. I've also opened this unit's relay and there are no signs of damage.

The machine has power and starts very well if it sits in shop for a couple hours and gets warm. Cold (sub-20 degree?) makes nothing work. No juice. I've tried batteries, charging system, relays, and major grounds. What the **** is going on?

Thanks.

 

[MrSEE]

The only thought I have left is to trace the power wire of the 24v/50A relay (under alternator) all the way back to the battery and see if there is a loose connection or damaged wire. Since the relay is functional, this is about the only thing I have left. Hopefully solved. Hard to do right now as it is rather cold in Eastern MT. Since this is a cold-weather issue I suppose it's best to see if can solve the problem outside of the shop.

 

[The FLU farm]

Battery cables checked. Fine. Grounds good on frame behind battery box, but we cleaned and tightened those as well. Also checked and cleaned the positive cable and traced up to starter

For what it's worth, my SEE's electrical system is also temperature dependent to some degree. No pun intended.
What caught me attention was your comment about the grounds being good behind the battery box. I thought that the ground went from the batteries to the disconnect switch, and then to ground.
I should've probably gone out to the garage and looked at the schematic before writing the above, but I must've got the idea that the FLUs battery disconnect is on the ground side from somewhere. Maybe from my own cable tracing, maybe from reading it.

I would try bypassing, or manually depressing, the clutch switch. It seems to be sensitive to low temps. Also, my SEE won't power the gauges (except oil pressure) until the alternator kicks in.
That makes the procedure become: Start, wait for oil pressure, then give it enough rpm for the charging to begin, at which point the gauges start working.
Of course, in my case the charging often goes upwards of 28-30 Volts until things warm up a bit. And that's summer as well as winter. Maybe more so in the summer.

 

[MrSEE]

Little update. Thanks FLU farm (have a couple wheels for you, but I must figure this out first).

This SEE is completely temperature dependent. It will NOT work sub-20 (I've been able to test more accurately with infrared gun). It does indeed seem that when engine block (just trying to keep one consistent point of measurement) is less than 20-25, there is no power.

As a note, you are indeed correct on the main grounding cable, but it goes right up to disconnect switch, and then right back to ground (next to where positive batt cable goes through frame) on the same route it came from the battery box.

I have noted when comparing to the other good SEEs... They tend to hit 24 on the voltmeter (or more... at least with the two others I tried) when key is turned. When this machine is "warm" it has power, but not quite 24. Not until it's been running. This leads me to believe it could be a short of some sort. A short circuit with less resistance could lead to less overall voltage, yes? (I only see this on the gauge when "warm", when "cold", nothing).

I've tested or exchanged all components in the main ignition power circuit, including: the starter, starter solenoid (replaced both with an extra), 24V/50A relay (ignition switch powers it been both replaced and bypassed for testing), alternator (original tested good by trusted and capable professional, also switched with another -used- unit), AC noise suppressor #1 (I get full voltage of batteries on the power side, plus grounds good... 0 voltage under power back to battery negative), not positive on AC noise suppressor right next to engine, but it is grounded well, and I ASSUME that it does not get power until ignition switch is ON, hence why I get no voltage with cab off and 5 cab connections OPEN. Ignition switch swapped with known functional unit. Fuses all new, connections clean (I clean nearly all accessible connections as a matter of habit on the machines I list for sale).

This all leads me to believe it is a wiring issue. Discontinuity or short. "Cold" dependent. So far I can say that the chassis minus cab looks good. I'll need to pull it into the cold and test it under those conditions. Leaning me towards a possible cab wiring issue. Won't know until I go try it all out under those conditions... that said, anyone who thinks they see something obvious... let me know. No reason to run around if I'm missing the obvious. Easy to put the blinders on when have a strange problem.

 

[The FLU farm]

As a note, you are indeed correct on the main grounding cable, but it goes right up to disconnect switch, and then right back to ground (next to where positive batt cable goes through frame) on the same route it came from the battery box.

Ah, that's good to know. I need to double check that connection on mine. Have used a good set of jumper cables to bypass the switch, but can't say with any certainty that it helped. And the switch does get warm...which could be from the trans.

I'll have to give your newest description of the voltage issue(s) some thought. About the only thing that comes to mind now is that your voltmeter reading is lower than what I'm used to (not counting the over ambitious charging I keep getting on one).
The HMMH, for example, likes to sit at about 28 Volts when warmed up. The (formerly) parts SEE sometimes goes to near 30 at times. Of course, all of this is on the assumption that the volt meters read correctly. I should check that, too, I suppose.
In your case, that you get a higher reading at the batteries than on the volt meter seems a bit odd.
Oh, one more thing; since you have access, maybe try using a battery load meter through the switch? That it shows continuity doesn't mean all that much in real life, right?
Or, try grounding externally like I did. It's quicker.

 

[Speedwoble]

My Mog #2 was intermittent at not starting. I tried directly shorting the solenoid at the starter. No love. I had the solenoid on the starter replaced for $25 at a local Amish shop.

FWIW, trying to diagnose it, I could have sworn I heard a large relay click coming from the Rt side of the engine compartment. I never tracked it down, nor checked it on the wall chart. It could have been an echo from the relays on the Left.

 

[Bikers33]

My Mog #2 was intermittent at not starting. I tried directly shorting the solenoid at the starter. No love. I had the solenoid on the starter replaced for $25 at a local Amish shop.

FWIW, trying to diagnose it, I could have sworn I heard a large relay click coming from the Rt side of the engine compartment. I never tracked it down, nor checked it on the wall chart. It could have been an echo from the relays on the Left.

That click on the right side is probably the intermediate shift valve on the transmission (hi-low). Or on mine, the valve for the ether can... but that one is more of a bang than a click.

 

[peakbagger]

Sounds like my old GMC Syclone in reverse. The exhaust header was way to close to starter which overheated the starter mounted solenoid. When it was cool it would work fine but once it got hot after a long drive the solenoid wouldn't engage. I pulled the starter and had it tested and it would work quite well. After a few attempts I finally had them replace the solenoid even though it tested out fine. It cured the problem until I sold it.

 

[The FLU farm]

Sounds like my old GMC Syclone in reverse.

Ah, that sounds so familiar (not that I had a Syclone, those were neat). And it's partially why I got into British cars for a while...to find out if the electrons flowing the opposite direction would help matters any.

 

[Speedwoble]

That click on the right side is probably the intermediate shift valve on the transmission (hi-low). Or on mine, the valve for the ether can... but that one is more of a bang than a click.

Interesting theories, but Neither of those should actuate with the starter button.

 

[MrSEE]

Got it figured folks.

I now know more than I ever wanted about FLU wiring.

It it isn't a positive answer, but believe it came down to the ground connection next to the #2 noise suppression filter. It was not completely tight. I suspect that during cold weather, not enough contact was made to allow current to pass to the main relay.

Tightened that connection, checked all wiring on chassis -particularly on left side of engine. Put cab back on and all was good!!!

This is whole process required getting some baseline measurements in the shop, a little electrical study, and a good multimeter. Then playing in the cold, where the problem showed up. Was pretty crappy to play outside during our recent winter storms. I'm sure the guys in North Dakota find this 0 degree stuff pretty funny...

anyhow... very hard to find. Amazing that something this small could create such an issue. The ground connection is hard to see even with the cab off.

Thanks for the thoughts and help.

As as a note, voltmeter reads lower than 24 but when leads to it are checked, I have battery voltage. I suspect the meter is culpable here.

 

[The FLU farm]

Congratulations, Mr. SEE!
Is it too late to point out that you could've cooled various sections using one of those spray cans with nothing but air, for cleaning electronics and stuff? Nah, I'm sure you have warm clothes.

 

[peakbagger]

Thumbs up! I expect your pain may help out someone in the future.