[Crosley]

I have used hundreds of the TransGo kits related to PWM lock up systems and not seen any damaged converter clutches

Sonnax products are quality stuff. Some of it is too labor intensive and tooling expensive

[monette999]

Have a tech 2 for the weekend need help to set it up correct.

What do I need to scan?

[monette999]

Originally Posted by Crosley

Down shift from what gear to ? .

Vehicle speed? On a Hill ?

Constant throttle and the trans down shifts for no reason?

You have a Tech 2 Scanner? What does it tell you? Live data stream scans?

Hello Crosley.
I have a Tech2 scanner for the weekend and I was looking for parameters I have to observe.

Here is my table what it should do?
I did not observed some weird switching on the scan tool, but I can see negative TCC speed.

Also I see tranny temperature, and I can do a snap shot.
Which parameter can give me good data to localize the failure?

SOL 1-2; 3-4 SOL 2-3 3-2 CONT SOL "Torque Converter
Clutch Solenoid"
1st ON 7V ON 7V OFF
2nd OFF ON 7V OFF
3rd OFF OFF OFF
"3rd Clutch
Converter Applied" OFF OFF ON 7V
4th TCC Applied ON 7V OFF ON 7V

[monette999]

Here my shift voltages which seems to be OK on the Tech2

[oldbogie]

Originally Posted by monette999

Here my shift voltages which seems to be OK on the Tech2

Look at the schematic. The computer not only provides a signal voltage but in several cases a relay to ground as well. A voltage applied to the actuation solenoid from the computer would not actuate the solenoid unless the ground was also provided. For the TCC there is also a temp switch inside the trans, they will hang up open which will prevent the ON signal voltage from reaching the solenoid. When this is dysfunctional the trans should shift 1 thru 4 normally but will only actuate the TCC whenever, or if-ever, the switch happens to close. A common quirk of this switch is that unless the trans is warmed up to an oil temp of 160 before the road speed is taken to 45 mph, it just won't close period, then you don't get lock-up till the trans temp cycles hot to stone cold to warmed up again.

Beats me, I didn't design it.

Bogie

[Rexnfx]

Originally Posted by Crosley

I have used hundreds of the TransGo kits related to PWM lock up systems and not seen any damaged converter clutches

Sonnax products are quality stuff. Some of it is too labor intensive and tooling expensive

Me too, lots of Transgo. Never had a problem with the TCC. Just something that Sonnax Tech posted to TRNW.NET

Uncle Gil, is the man

I like using Sonnax and got alot of the tooling, it helps me to feel a little more like a rebuilder instead of a parts changer Blending the two is really fun. Long as you get paid for it.

[monette999]

Crowsley
now I can present some better data.

Hope you can help me out.
Sorry I cannot upload the SUR file.

Here the 4L60E failure mode
I am driving constant speed,
and the 4L60E is shifting down into gear 3. The PCM still listed gear 4. You can see Engine Torque, gear ratio & engine speed changes.

Today I also got a falure code P 1870. WHen I looked inot the engine snapshot not inportant information was present which gave an indication of failure mode.

[Crosley]

The PCM provides grounds for solenoid activation.

A solenoid can fail 2 ways. Fail electrically or hydraulically

Your photo indicates the PCM is commanding 4th gear

The graph indicates RPM changes that would indicate a shuttle shift from 3rd to 4th... back to 3rd , then back to 4th.

There can be multiple cause:

Wire problems = ground is lost to solenoid. Could be wire from PCM down the chassis to the trans OR wire problem inside trans case. Old wire harness inside trans can cause many problems and not all show up on scanner

Solenoid may be hydraulically failing and not maintaining 4th gear. I have seen this problem more in 4L80e trans

2-4 band may be faulty, not holding power. 4th gear servo may not be holding pressure and the 2-4 band can not maintain 4th gear.

4th gear accumilator leakage and loss of pressure allows the 2-4 band to disengage and not hold 4th.

My best guess at the moment.

code p1870 was discussed earlier.. my same comments apply

[monette999]

Wire problems = ground is lost to solenoid. Could be wire from PCM down the chassis to the trans OR wire problem inside trans case. Old wire harness inside trans can cause many problems and not all show up on scanner

Thank you for the good advice,
Is the PCM watching the current flow thought the solenoids, or does it only monitors the level on the microcontroller.
Short to ground the controller output is pulled down to zero
Intermittancey the controller see high output.

BR
Monette999

[monette999]

HI Crowsley
I also read in the service manual that a bad TFP Switch can cause this problem. Have you experience high defect rate on a TFP switch?

BR