Resistors on transmission?

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jarred15801
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Joined: Sat Apr 05, 2008 3:03 am
Car: 1997 Infiniti Q45

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Where do i find these resistors? and how do i find the "dropping" one?



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Raxephon
Posts: 1910
Joined: Tue Jul 27, 2004 8:53 am
Car: '04 RX8...for the moment...

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Dropping resistor is in the engine bay of the G50 series Q45 and in most other Nissan/Datsun/Infiniti models.

It shows you where the electrical components are in the Factory Service Manual, so you really should get one. (The pdf file is easy to find if you just look around abit.)

My dropping resistor was here.

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qsiguy
Posts: 1961
Joined: Sun Mar 20, 2005 8:12 pm
Car: 1994 Infiniti Q45 Turbo

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Not sure where it is on the '97 model but mine is where anlasak said it was near the battery. It's a little tough to get to.

What's your reason to locate this resistor?

jarred15801
Posts: 159
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Car: 1997 Infiniti Q45

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When i start out from a stop and im going pretty slow like about 10mph say from a light or in a parking lot, when the car goes to shift into 2nd it's like it slips or doesn't catch 2nd gear. I don't believe it's actually slipping though becasue under heady acceleration it does not do it at all. A member on here said it looked like a low pressure line issue. he said if id unplug the dropping resistor that it would run at full line pressure. and i could see if that really was the problem and that it may keep my tranny alive longer.

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qsiguy
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Car: 1994 Infiniti Q45 Turbo

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Well, without feeling it first hand I couldn't tell you if it was a bad slip or just the normal easy shifting these cars do under a low load. The main time slipping will do damage is under a high load.

As far as testing this issue by disconnecting the resistor that is ok. If it will keep your tranny alive longer is debatable. I don't recommend just leaving it unplugged all the time. You will get a "transmission malfunction" indicator every time you start the motor and the shifting is really hard, at least it is in mine. I currently have mine wired to a relay which is controlled by the kick down switch so when I am at WOT the resistor is disconnected and I get solid shifts when under hard acceleration/full boost situations. Every time I start the engine when during the previous drive I went WOT even once, I'll get the "trans malfuction.

My next experiment is to just add resistance to the circuit instead of complete disconnection, and see how much resistance I can add before getting the malfuction light. Hopefully before I get the malfunction light I will be getting slightly firmer shifts.

jarred15801
Posts: 159
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Car: 1997 Infiniti Q45

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It's not the normal easy shifting these cars do, if im going about 5 or 10 mph and not trying to go any faster then that, when it goes to shift into second it doesn't catch and just revs around 2500-3500rpm's and then it catches 2nd and the rpms drop back down. I don't believe it's slipping because it only does it at times like this. it never does under heavy acceration. does anybody know where the resistor is on a y33?

Q45tech
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Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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After you do a pan drop filter replacement, clean and replace all the ATF then add 1 bottle of LubeGuard RED to ATF.

http://www.lubegard.com/testimonial.htm ... s_atf.html

maxnix
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Joined: Mon Jul 22, 2002 8:11 pm
Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45

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Without any transmission maintenance history nor mention of an auxiliary ATF cooler nor condition of ATF, it sounds like you have a transmission problem, not a resistor problem. Best address the deferred transmison maintenance first.

jarred15801
Posts: 159
Joined: Sat Apr 05, 2008 3:03 am
Car: 1997 Infiniti Q45

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Well i just bought it with 100k on it and have only put on like 1500 miles. it was serviced under warranty up to 70k miles. A couple months ago i had the transmission flushed and filled with mobil 1, and the filter done also. I know what a slipping transmission feels like, but this isn't the same. anyways i found a used transmission out of a 2000 with 40k miles on it for 375 shipped. So i might take advantage of that.

Q45tech
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40k AT for $375 is a deal even if you just keep it in garage for that day.


maxnix
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1995 Infiniti Q45t
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Sounds like a good deal. Replace the turbind sensor and rear seal along with fluids and interior filter before you install it.

Q45tech
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Resistors are installed to absorb the stress on TCU switching transistors when the solenoid is deenergized [shut off]...................removal may stress these transistors to the point of causing a TCU failure.

The resistor delays the solenoid drop out time and suppresses the energy spike [at TCU] by about 1/20 or 95%.

REMOVE the resistor at your own risk if you are always lucky at gamb|ing.http://relays.tycoelectronics....1.pdf

Just like old fashion ignition points when you open the points the solenoid coil magnetic field collapses and induces a very high voltage spike backwards across the points and burns them up [without the capacitor across the points to store the shock [reverse spike]].http://relays.tycoelectronics....4.pdf

Neither of these pdf are perfect to explain the resistor across the solenoid but a relay or coil is just like a solenoid so they should give you the correct idea.

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qsiguy
Posts: 1961
Joined: Sun Mar 20, 2005 8:12 pm
Car: 1994 Infiniti Q45 Turbo

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Do you happen to know the tolerance of the TCU in regards to the resistor? What is the nominal range and at what resistance does it send the "transmission malfunction" code? I was going to experiment with this but if you have the numbers in that huge noggin of yours that would save me some trouble.

maxnix
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Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45

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Thank you for the analogy to the capacitor on a points system. I would never have guessed being essentially electronically illiterate.

Q45tech
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In a way any coil is a coil even a Tesla Coil:http://eece.ksu.edu/~gjohnson/tcchap6.pdf

Why not use a "clamping diode" in place of resisitor to protect TCU

"Turn On TimeThe time constant for a circuit with inductance and resistance is T = L / R, so for this clock that's .39 H / 10 Ohms = 0.039 seconds or about 40 ms. It takes about 3 to 5 time constants for the value to settle so let's say it's in the 0.1 to 0.2 seconds area. "........................"When the current is stopped the coil generates a voltage spike that's opposite in polarity from the polarity when the coil was powered. A common way to protect a transistor that's driving a relay is to place a diode across the coil with the diode back biased during normal drive so that when the voltage spike happens it will be shorted out in the diode. This same method will keep the points in a mechanical clock from arcing.

This will slow down the time it takes to discharge the coil. The time constant is the same as calculated above or about 0.1 to 0.2 seconds. So even when these are added toghther they are still much less than a minute.".............................."As current goes into an electro-magnet it charges the magnetic field. If the current is stopped the magnetic field collapses generating a current in the opposite polarity but starting out at the same value. If there is no snubber circuit across the coil the voltage can be very high. This causes arcing on the mechanical points controlling the current input, wearing out the points.

By placing a resistor in parallel with the coil about five to ten times the coil resistance the voltage across the coil at the start of the back EMF will be five to ten times the normal coil voltage and so eliminates the point arcing problem"

Obviously they chose a resisitor to delay the solenoid change time not just to protect TCU, as many circuits in Q use multiple diodes to blow main fuses when battery is jumped BACKWARDS and diodes to protect electronics from reversals!

So maybe some of both a reverse clamping diode [100 volts and a few watts] and a higher resistance resistor x2, or x 3 pr 4x OEM to reduce the spreading of electronic vs mechanical time.

One would use a digital oscilloscope to few and time what happens.

Secure 2-3 from junkyards and try them in series for 2x and 3x.

Q45tech
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Posts: 14365
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

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FSM says solenoid is 2.5-5 ohms depending on temp and resistor is 11.2-12.8 ohms SO 3.75 vs 12 averages or the resistor is 3x larger than coil resistance.

We need to know the coils inductance [with an inductance bridge] since we cannot use the simpler method of holding the valve on solenoid stantionary or maybe this:http://www.coilgun.eclipse.co.....html

The coil might flow 3.7 amps once the valve has opened and the resistor will flow about 1.2 ampere all depends on solenoid temperature [174F] and resistor temperature [130F]................remember the supply voltage will be 13.8 since rpms are high..............and 4.84 is total potental current flow.

What we also don't know is how much reverse pressure the ATF/valve body applies to try and stop the solenoid from moving..............a 50 watt solenoid is strong.

http://www.magnet-schultzameri....html

Drill down and look at diagram of pressure control solenoid see rear calibration screw?:http://co-5.college-online.com...1.doc


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qsiguy
Posts: 1961
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Car: 1994 Infiniti Q45 Turbo

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Wow Tech! Thank you very much for that excellent information. No offense toward most of your other posts, but in my opinion this has to be one of the most informative, unbiased, posts you've made. You've shared theories on how it works and how you feel the mod could possibly be done safely regardless of the potential for people to mess up the car. We all know there is risk in any mod but some of us will try things anyway.

Sorry to carry on like this but I'm just so excited to see those posts! I was starting to believe you wouldn't offer helpful info if it strayed from how Nissan did it originally. Hope you don't take any of this post the wrong way, I really am just happy to read that info.

I use diodes all the time to shunt voltage spikes in relays. This is some great food for thought and now I have some new research and testing to do with your guidance and inspiration.


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