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Geo Tracker Sending Torque Converter Clutch Solenoid Code

Geo 4x4 Geo Tracker repairs

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6 replies to this topic

#1 rent24

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Posted 13 July 2013 - 09:14 AM

I have a 1997 Geo Tracker 4x4 and have changed the TCC Solenoid and the TCC Relay. We clear the code and drive the car and the code comes right back on. I am trying to get the car inspected. Does anyone have any ideas?



#2 Moses Ludel

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Posted 14 July 2013 - 10:27 AM

Hi, 'Rent24', and welcome to the forums!  While I'd like others to participate and share their experiences with the TCC system on the Tracker and Sidekick, I'll jump-start this discussion... 

 

Since we're talking about the torque converter lockup here, let's begin with whether the torque converter is actually locking up.  You should have the 3-speed automatic with TC lockup.  The rule here is that the engine speed should be around 3400 rpm at 70 mph with the converter locked.  If it's around 4,000 rpm at 70 mph and cruising throttle, the converter clutch is not locking.  Rule out vacuum modulator vacuum leaks—a defective modulator or leaks will affect shifting points but typically not the converter lockup. 

 

You have replaced the relay and solenoid, so instead let's focus on the torque converter and wiring circuit.  From your description, you must be getting the PO740 diagnostic troubleshooting code.  If the converter clutch is not locking, and the converter itself is not defective, the problem is likely the wiring.  I would check the wiring circuit carefully with a volt-ohmmeter, since the P0740 OBDII code is related to the "circuit" for the TCC system.

 

What you want to do is check for voltage and also continuity and resistance.  I would isolate plug-to-plug segments of the wiring harness leading to the TCC relay, solenoid and the converter itself.  Begin with a wiring schematic for the system and determine the current flow for the TCC circuit.  In the transmission section of a shop manual, you will find a description of the transmission's shift modes and also the lockup point and functions of the torque converter.

 

Continuity and resistance (ohms) for a given wire(s) should be checked without the battery hooked up.  Disconnect the battery ground cable before running these continuity/resistance tests.  When you run the voltage tests on live circuits, you may need the key on; however, the engine should not be running.  Even if the Tracker is parked, you should chock the tires, use the parking brake and exercise the usual cautions if you test the wiring circuits in the various gear selector/shifter positions.

 

At plug socket voltage checks, you should get nearly the same voltage as the actual battery voltage (without the engine running).  If voltage "drops" significantly between the battery and the plug being tested, there's either an open or too much resistance—or there could be a poor ground in the system/circuit.  On a 12-volt D.C. system, ground circuits are as important as hot or positive side readings!

 

Voltage drops, especially the ground circuits, can be tested with a "lamp load test", too.  This is a relatively simple way to test wiring circuits, both negative and positive.  You can use an old headlamp for this test...On lighter gauge wiring, use a smaller light bulb that draws less amperage.  Tractor auxiliary lamps often work well here.

 

Begin with testing the lamp's glow when using a heavier circuit like the starter motor's cable and a good ground.  (Never generate sparks near the battery!)  Note the lamp's brightness.  Now test the TCC wiring circuit in question.  See how brightly the lamp burns.  If dimmer, there is a voltage drop in that circuit.  The drop can be corrosion, wear, an open or short, or simply bad connections.  Always make sure you use good grounding points when running lamp tests—this is D.C. and requires quality grounds.

 

If wires test okay, make sure connections are clean and not corroded.  Corrosion and corrosive "wicking" up the wiring insulation is a common issue in the Rust Belt and four-season climates with salted winter roads.  Use an electrical contact cleaner to remove corrosion, and be sure the plug connectors are free of corrosion and fitting snugly.  I use fresh dielectric grease on the plug contacts to keep moisture at bay—inexpensive insurance!

 

Since your P0740 DTC reading is consistent, you may have an open in the wiring circuit.  The most valuable diagnostic tool in this case will be a digital volt-ohmmeter.

 

Others are encouraged to jump into the discussion...Trust this helps, Rent24, let us know what you find!  Looking forward to your posts...

 

Moses



#3 rent24

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Posted 14 July 2013 - 02:39 PM

Moses

Thank you for your all of your information.I will follow your advice and let you know how I make out.

Richie



#4 Moses Ludel

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Posted 14 July 2013 - 03:16 PM

Richie, you're welcome...The things I shared can be considered the "methodical" troubleshooting approach.  I like to work through "no cost" solutions before doing the "parts changing" routine. 

 

I think you'll nail this on the next round...Please keep us informed, others can benefit.

 

Something everyone needs to know about OBDII and code readers is that these codes are only a rough view and suggest defective "devices".  If the wiring or plug connections on these circuits are faulty, OBDII delivers the same trouble code.

 

When you go to a dealership or well-equipped independent shop that has higher end diagnostic tools, the test equipment is way more than a "code reader".  OBDII scan tools like Chrysler's DRBIII can actually interrogate and operate individual devices like the idle air control motor or individual sensors.  These kinds of tests sometimes make it cheaper to pay a shop to test the system than when you use an inexpensive code reader and begin a parts replacing approach.

 

Looking forward to your topics and posts!

 

Moses



#5 rent24

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Posted 03 March 2014 - 07:16 PM

Moses

I just got back my Tracker (7 months in the shop).The TCC solenoid and TCC relay were changed.the it was sent to the tranny shop to pull the transmission ( twice) and the Torque converter was changed.Cleared the TCC code and passed inspection.I drove the car home(@ 50 miles) turned on my block and the check engine light came back on.I plugged in my computer and the same TCC failure code is now back on...

Richie



#6 Moses Ludel

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Posted 04 March 2014 - 10:45 AM

Richie...Sounds like a wiring harness or plug connector issue.  You've replaced the target parts, the transmission's converter being the capper.  Look over the wiring harnesses and plug connectors.  Any possibility of corrosion within these connectors? 

 

Any plug contacts with a black surface cast are oxidized and will create resistance—which can trigger a code.  Use a good electrical contact cleaner or soda blasting (if such equipment is available) to remove just the oxidation—no heavy abrasive or sandpaper here!  You want clean smooth contacts at these connectors.

 

You can test for wire continuity and possible internal "opens" with a volt-ohmmeter.  Check wires over the full length of a harness, end to end connections, with the ohmmeter.  Resistance will show up, and you can narrow it down.  If you suspect an internal flaw within a harness (like at an exposed or curved area of the wires), try wriggling the wire while testing ohms resistance.  (This may take two people to keep an eye on the ohmmeter and also wriggle the wire.)  Sometimes an open will only occur when a wire or plug connector flexes—like when turning the vehicle onto your block and torqueing the engine!

 

Good that you've replaced parts known to fail.  Sounds like the solution is near at hand, you made it nearly home before the code threw.  Check the connectors and wiring.  We're available for further comments and suggestions, Richie!

 

Moses



#7 rent24

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Posted 06 March 2014 - 03:10 PM

Moses

 

TY..I appreciate the help.....

Richie





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