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Fresh test results.
Level freeway with almost no traffic.  
60mph in third gear for about half a mile, then very gently apply more throttle.  
The tach started to climb immediately then speed began to increase

60mph again, then gently lift throttle.  
Tach stared to fall immediately then the vehicle began to slow.

When repeated in OD, the RPM barely moves at first then jumps noticeably.

Is this vehicle equipped with a tow-haul mode?

No tow-haul mode

Actually seeing an RPM slight jump before speed builds indicates to me the system is cancelling the lockup , then you see a speed increase.  Perhaps I misunderstand your statement?

If the throttle is slowly applied while in third, there a smooth increase in RPM right from the moment the throttle starts to advance, no hesitation then jump as I would expect to see as the converter goes from lock up to open.   It behaves just like an older style trans without a lock-up.

There is a road close by that starts flat then becomes progressively steeper.  I will drive in third with constant throttle and watch if there is a blip in the RPM as the road becomes steeper and the engine starts to labour.

I guess you are talking about a 4L60E transmission?

Yes, my late night typo.

Are you having an over heat issue?

So far I have only towed very light trailers that would not exceed 800lb a few miles from the hardware store with this particular car, and never had the slightest problem but I am planning to haul a 2500lb boat about 400miles and as the trans has done 125,000 miles I want to avoid punishing it.

The factory programing has the converter clutch (TCC)  applied in 3rd gear. If you step  on the throttle enough the TCC is released.

That is what I was expecting, however even if I gently feed in the throttle, the engine RPM starts to climb up before the vehicle speed responds suggesting the convertor is open all the time.   Is there any other simple test I can perform.

Question relates to a 2004 460LE when towing.

My feelings are that it is better to tow in third gear rather than OD because it takes the load off the OD planetaries and clutches, also allows the engine to run a little faster.

However, if the convertor does not have lock up in third, then it will continue to churn and pump additional heat into the fluid.

So, the question is, does the convertor ever lock up in third (direct) gear?  I have run in third and definitely cannot feel a lock up and the tach starts to climb with even the tiniest increase in the gas pedal.

If the factory config does not provide this,
is there pressure available to the OD lock up valve when in third,
and if so, would it be feasible to tap into the external harness and activate the solenoid manually.

Today I got an ohmmeter that would read milliohms, and come up with .002 milliohms for about 10 seconds, then it dropped to zero. So I am thinking there is no Shunt in it, and was probably in the original wiring to the meter.

Apologise for not responding earlier, it has been a crazy last few months.

Although a resistance test would have seemed harmless enough, real care has to be exercised with ammeters out of circuit and I am afraid if it was a remote shunt type, the ammeter may now be defunct.

The coil in the meter movement of an ammeter requires an extremely small current to drive it to full scale.  

Multimeters push a current through the item under test while making a resistance reading.

When applied across the terminals of an ammeter with internal shunt, the current generated by the multimeter passes harmlessly through the shunt and the ammeter needle will not even blink.  But when applied directly across the terminals of an ammeter intended for a remote shunt, the injected current goes straight through the coil and may be many times the maximum current the coil is designed to carry; the ammeter needle swings to full scale and after a very short time the coil burns out.

If an automobile ammeter does not have a heavy copper strip running across the back of the case between the terminals it is likely intended to have remote shunt and must be handled with care until fully wired up.

However before being a complete predictor of gloom, something does seem a little odd with your readings.
When you say the reading was 0.002 milliohms, was that a typo, should that be .002ohms.  And,  it dropped to zero, do you mean the meter showed 0.00 milliohm, or it showed no reading at all indicating an open circuit.

When you ran the test could you see the meter dial or was it lying face down on the bench.  It would be good to know if the needle jumped at all during the test.

The second alternative I have is using an external shunt to reduce the current through the Ammeter to reduce the deflection by 2/3 so the meter is not damaged by excessive Amperage. But this still requires bringing a potential 100 amps of current into the cab.

If you can remove the existing shunt, you can install a new shunt of 1/3 the resistance in the engine bay and just bring in a pair of thin wires to the meter. This avoids running high current cables into the cab.  As additional security you can fit an inline fuse in both meter wires close to the ballast.

I want to convert an ammeter to a voltmeter.  I should be able to calibrate it to read 12 volts at the center (zero) and show a charge over zero when being charged, and under zero when discharging.

Am I barking up the wrong tree? It sure would solve some problems.

Well, it can be done, but there is a lot of fiddling.   I have been cheeky enough to slightly reword some of your text to make it a little easier to follow.

In the case of an ammeter the movement is wired in parallel with a resistance (shunt) so only a portion of the load current flows through the meter itself, the rest goes through the resistor.
Ammeter splits the current
Very small portion through the movement (about .0001A)
Most through the parallel shunt

In the case of a voltmeter the movement is wired in series with a resistance, so only a portion of the voltage is across the meter itself, the rest goes across the resistor.
Voltmeter splits the volts
Very small portion across the movement (about .01V), most across the resistor

The first step is to remove the shunt.

If it is the type with a remote shunt as used on some Dodge trucks, then that part of the job is easy.  If it is the integrated type, the shunt may be on the outside of the case across the terminal posts, -not too difficult to remove.  If it is the integrated type with the shunt inside the case, then the case has to be opened.

OK the shunt has been removed, now to convert it to a voltmeter and the fun really begins.  

As a voltmeter, you want the needle to be at the max discharge end of the scale when no activity, and mid point at 12V. But on the donor ammeter the needle sits in the middle when no activity.

There is a way to build a circuit that would force the movement to be at the max discharge end of the scale for say 9V, in the middle for 12V, and at the max charge end of the scale for 15V.  Not too difficult but quite a bit work for a one-off.

The other option is to remove the glass front, pull off the needle and reset it.   Initial instinct is to reset the needle to the max discharge end of the scale when no volts applied and tweak the series resistor so the needle is at mid position for 12V and continues into the charge region when the battery is above 12V.

But remember the movement originally went from zero to max over half of the full scale range. If it is made to go from zero to max over full scale, the movement is being forced through double the designed travel, -- some movements will cope with this, others will not.

So the safer option is to reset the needle to the half discharge reading at no volts then tweak the resistor to give mid point at 12V.  The disadvantage of this is that the sensitivity of the meter is quite low and I doubt it would be of much use.

Here is my attempt at how I would wire it.

Only two comments.
1. If the relay coil supply is connected to the downstream side of the fuse rather than directly to the battery, (or jumpered at the relay),  then all the wiring is protected.

2. If the vehicle has a computer controlled engine, or BMC, it would be prudent to use a relay with an internal diode across the coil to suppress the high voltage spikes generated on release of the relay.

Well, I tried this at the end of a trip after the trans fluid was up to operating temperature.    The vehicle moved about two inches instead of about 3 feet when cold.

Thanks for the explanation.

The clutch packs are "applied " via the oil pressure from the pump.  Not disengaged.

That is what I always believed and made this seem so strange.

You will see this more in colder temps than warm, simply because the oil is slightly thicker.

I suspect this has occurred after the vehicle has been parked and everything s cold, as an experiment I will try this after a trip when the transmission oil is warm.

I also relay  start  circuits on automatic vehicles .  It is a long run of wiring  from the neutral safety switch loop from ignition sw to starter solenoid  . I had a hot start issue with one of my 66 Mustangs  fitted with the non clapper starter motor ,the starter solenoid was inefficient with heat,not helped by old light gauge wiring.    Used a relay to apply the "start" 12v and for 10 years it has not missed a beat.

Even a vehicle with manual trans benefits from a relay on the start circuit.   The current drawn by the solenoid is quite significant. It punishes the contacts in the ignition/starter switch and on vehicles with a harness connector in the firewall the large current flowing through the connector (simultaneously in both directions) contributes to the deterioration of the connector body.

My daily driver has a 460LE transmission.    It has never caused any problems but from new has displayed something weird.

If the motor is started with the trans in neutral, vehicle on level ground, both foot brake and park brake released; the car moves forward about 3 feet then rolls to a stop.

I normally have my foot on the brake when starting, so can not remember how I first came to notice this, and just out of curiosity I have repeated the exercise a few times over the years always with the same outcome.

It is as if one of the forward clutches is engaged until the pump builds up pressure.

Do you have an explanation Crosley?

My headlights are not as bright as they should be. I am running King Bee headlights with halogen lamps. A street rodder acquaintance of mine suggested running my headlight wiring through relays. Will that make that much of a difference in terms of brightness?

Before embarking on any wiring modifications, check the condition of the lamp ground wire and its connection to the vehicle body.   Lighting problems are often caused by poor grounding.


https://www.danielsternlighting.com/tech/relays/relays.html

A couple of comments regarding the lighting circuit shown in the link.

If there is a fault condition anywhere along the relay feed or the wiring between the relay and the lights, the fuse will blow and leave the driver without any lights.  This could be disastrous while driving at night on a poorly lit road.  

Rather than a fuse, it is better to use a self-resetting circuit breaker.   In the event of a fault, the breaker will quickly cycle on-off preventing major meltdown while still providing intermittent bursts of light while the vehicle is brought to a stop.

Power for lighting relays should be taken from the positive battery post rather than the alternator terminal.   The battery will provide a more consistent voltage leading to longer bulb life.

While it is preferable to replace the wiring between the relays and the lamps with a heavier gauge, just eliminating the long run of skinny wire from the battery to the light switch then to the hi-lo switch and along to the front of the car will make a huge difference; and also increase the life of the switches.

I currently have an under floor mounted non power assisted master cylinder with a 7/8" bore and I am thinking of installing a 7" power assisted master cylinder setup with a 1" bore.


The pedal is firm and the car stops adequately but I cannot lock the brakes up no matter how hard I depress the pedal.

Remember, if you change from a 7/8" to a 1" bore, that by itself will increase your pedal effort by 30%.     A single diaphragm booster will barely compensate for the additional pedal effort due to the larger bore master cylinder.    You will need a dual diaphragm.

Well, it is 15 minutes past midnight here, so I can be the first say Merry Christmas to all --on the day!!.