A340F Trans - P1700...but NOT Speed Sensor - Toyota Nation Forum : Toyota Car and Truck Forums
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#1 Old 10-10-2012, 06:53 AM
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A340F Trans - P1700...but NOT Speed Sensor

My red '98 4wd T-100 is still a real "looker", with a modified/SC 5VZFE and the automatic trans. I am the original owner. I do all work myself, unless it's over my head, or I can't endure the down-time. It's my DD.

After about 149K miles, the flex plate cracked and I needed to replace it. I also had a mild torque converter whine, so I sent the converter to IPT for a total rebuild, since they did the VB and are excellent with transmission work of ALL types.

The shade tree mechanic that did the trans R/R for me was a "friend of a friend" that manages an AAMCO, (but was not ASE/Toyota certified). I was told he was good and meticulous. I was lied to.

Anyway - when the converter came back and the re-install work progressed, I came to regret using this guy at all. When he called me to come get it, I went immediately, even though it became obvious to me that he hadn't even test drove it after the work!

I REFUSE to take it back to him - even though the issues I am now reporting "came to be" only after his "work" on the vehicle was performed.

After I got it back, there were 2 major issues. The minor ones, (such as line pressure cable and shift linkage adjustments) I did myself - and they got the truck into good running shape. BUT...even though the basic peformance of the truck seems great, I get (2) indicators saying otherwise.

On occasion, when I park it - The "A/T P" dash light comes on. Yet it seems that the park pawl is engaged properly - as it should be. I never saw this light before - didn't even know of such. This happens rarely, but it does happen.

Much more often, I also get a MIL (CEL) storing a p1700 code. This happens about 1 time per drive to/from work - which is about 20 miles each way.

I inspected the wiring from the ECM to the #2 speed sensor - and I also replaced the sensor, but it made no difference. I have the Toyota full set of FSM books for the truck and have tried tracing the circuits out repeatedly without reaching the true solution.

I use either my "tuning laptop" or my "Ultragauge" connected to the OBD II port to reset the MIL, but this routine is a real PITA. In FACT - I have NEVER had any such issues with the truck - especially not MIL codes, or dash lights - before I got it back from this trans R/R.

It runs, shifts, & drives fine. But I am out of ideas. I even swallowed ALL pride and took it to my local stealership, (who kept it all day, wrote it up as "NPF", and charged me $105).

Easy answers include either "it's a bad "ECM"" or "intermittent wire harness". Please: save your time and trouble, if either of those are your ideas.

I would rather hear from someone who "KNOWS" - from a similar experience, (since I can "guess" pretty good myself if I wanted to make a game out of it).

Thank you!
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#2 Old 10-10-2012, 09:27 PM
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H'mmm, that's a tough one.
When the TC was rebuilt and replaced, was anything done to the trans?
The fact that AAMCO touched it is scary.

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#3 Old 10-11-2012, 03:46 AM
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I have the EXACT same problem on my 1996 T-100...long bed, 2WD, auto, 3rz-fe (4 cylinder). I've even measured the sensor it it works as it should. It is a salvaged vehicle as it had extensive damage to the right side. Haven't been able to trace the problem down either.

I'm thinking the harness got damaged or stretched at one of the connectors. I have yet to measure the resistance at the wiring connector. I'll have to compare it to my 1998 T-100 auto xtra cab 2WD 5vz-fe (V6) measurement. What resistance values did you come up with?

My option is to run a separate wire from the sensor directly to the ECU and see if I can isolate if it's a particular wire.

1998 T-100 SR5 2WD auto, Roadmaster Active suspension, oil catch jar, AC mod, aero cap, lower aero package, 67% grill block

Last edited by BamZipPow; 10-11-2012 at 03:50 AM.
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#4 Old 10-11-2012, 06:33 AM
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Thanks for your inputs. I appreciate the brainwaves.
Amendment for the 2 good questions/comments posed:

1. My transmission itself has had no ills, nor have I seen any MIL before the removal/replacement was done. I share your fears of the AAMCO reputation. I tried like hell to find a trustworthy shop locally and failed. However, "AAMCO" technically did not touch the tranny. But the "friend-of-a-friend" (that did the work) happens to manage an AAMCO - and for years prior did work as a mech there. But the task on my vehicle was strictly R/R, with no discrete tranny disassembly. It was all done at his home shop, where he "moonlights". Perhaps this is worse since no legal help is possible, if I wanted to try that route. The guy wanted me to bring it back in after I reported the list of woes....but I refused. Our deal was for him to do the work, thoroughly test it, call me when it's DONE & ready. After I drove it and it was obviously in need of further/finer care.....I paid him off and left there for good. That chapter is over.

2. Although I verified the #2 speedsensor signals are present on the OBD II bus, it is little help, since the problem shows up intermittently. I believe the MIL latching "on" and the P-code being stored indicates a large number (500?) of incorrect (or missing) pulses were encountered, and perhaps even "randomly" - over an unknown period of time. Replacing the sensor was my way of eliminating it, (especially since there was "some" evidence to suggest it might be the cause). But that would be too easy.

My prevailing theory at this point, (as mentioned) is also that the harness may have suffered somehow during the work. My next "plan" is to route an external shielded pair cable from the sensor connector to the ECU connector pins. However, I am not sure "when" this will be. Time is tight right now. But it is interesting to hear that someone else has this problem....(BZP). Any history there?

Last edited by MJfromMD; 10-11-2012 at 06:40 AM. Reason: Errors in structure
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#5 Old 10-11-2012, 09:11 AM
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I personally don't drive the "other" T-100 as I got it to replace the 1993 T-100 that someone hydrolocked. Currently the step-daughter drives it so I don't have access to it to test with. I do have a CarChip hooked up to the ODBII bus so I do have limited data when the code sets.

Here are two examples from the CarChip...

View / Vehicle Trouble Log / Record Problem 8
Overview
Time : 01/31/2012 10:41 PM
Vehicle : 1996 T-100
CarChip : N-0063-D
Trouble Code : P1700
Description : Unknown Powertrain DTC (Manufacturer Controlled; Transmission)
Comments :
Engine Status
Fuel Pressure (Gage) :
Intake Manifold Pressure (Absolute) :
Engine Coolant Temperature : 109.4 F
Calculated Load Value : 36.5 %
Engine Speed : 1,708 RPM
Vehicle Speed : 30 MPH
Fuel Trim Status
Short-Term Fuel Trim (Bank 1) : -2.34 %
Short-Term Fuel Trim (Bank 2) :
Long-Term Fuel Trim (Bank 1) : 3.13 %
Long-Term Fuel Trim (Bank 2) :
Fuel System Status
Fuel System 1 Status :
Fuel System 2 Status : Closed loop; using oxygen sensor(s) as feedback for fuel control.

View / Vehicle Trouble Log / Record Problem 9
Overview
Time : 03/29/2012 07:18 PM
Vehicle : 1996 T-100
CarChip : N-0063-D
Trouble Code : P1700
Description : Unknown Powertrain DTC (Manufacturer Controlled; Transmission)
Comments :
Engine Status
Fuel Pressure (Gage) :
Intake Manifold Pressure (Absolute) :
Engine Coolant Temperature : 129.2 F
Calculated Load Value : 20.0 %
Engine Speed : 1,298 RPM
Vehicle Speed : 27 MPH
Fuel Trim Status
Short-Term Fuel Trim (Bank 1) : -2.34 %
Short-Term Fuel Trim (Bank 2) :
Long-Term Fuel Trim (Bank 1) : 3.91 %
Long-Term Fuel Trim (Bank 2) :
Fuel System Status
Fuel System 1 Status :
Fuel System 2 Status : Closed loop; using oxygen sensor(s) as feedback for fuel control.

It is random and the data that I have doesn't point to particular speed, temp, or time. Of course once the code sets, the CarChip doesn't automatically reset it to figure out when it happens again...I have to manually reset the code.

I'll have to find time to put the truck back up on the ramps so I can visually trace the wiring harness and see what is really going on.

1998 T-100 SR5 2WD auto, Roadmaster Active suspension, oil catch jar, AC mod, aero cap, lower aero package, 67% grill block
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#6 Old 12-05-2012, 05:47 AM
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I have traced/confirmed the harness, connector, pins, and continuity from the sensor to the ECU plug. Also confirmed the Neutral Safety switch connection/wiring and proper operation/indicators of the transfer case shifting thru H/L ranges. I can't believe it could be the ECU itself, but I am runnin outta road.

This one has got me bad. It's a real PITA to keep resetting the CEL and yet it drives fine. Wish an A340F Guru would step up with the answer for this one.
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#7 Old 12-06-2012, 02:52 AM
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Is there a way to record the pulses over time/speed? At least it would give you a graphical view to isolate what could possibly be the problem. Since it is a Hall effect sensor, it should be fairly easy to hook directly up to the sensor and record it from there.

Is it possible that the sensor rotor inside the transmission could be loose or even broken? According to my 1998 FSM, the removal/install procedure is on page AT-4 through AT-6. There seems to be a lock ball fer the 5VZFE and a lock key fer the 3RZFE. Not sure how it could be broken or damaged. You might be able to check fer play/looseness if you pull the speed sensor and use a small screw driver to see if you can move/rotate the sensor rotor.

If you need to replace the lock ball, it looks to be pretty simple to pull the transmission mount, extension housing (tail piece), and speedometer drive gear off. You'll need a new gasket fer the tail piece as well as some Loctite 242 fer the tail piece bolts. The two bottom bolts fer the tail piece are shorter.

Does yer Ultragauge show the proper road speed when the code is set? I can't remember if the ECU uses the Speed Sensor 2 in the speed calculations or not.

1998 T-100 SR5 2WD auto, Roadmaster Active suspension, oil catch jar, AC mod, aero cap, lower aero package, 67% grill block

Last edited by BamZipPow; 12-06-2012 at 03:47 AM.
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