TCC Switch In, Check Engine Light On!!

[Thomas C Potter]

In effort to have the TCC lock up later and at my command, I tapped into its wire and mounted a switch on the shifter. Works well. HOWEVER, the ‘check engine’ light is now on constantly. My concern is that after a period of time, set by Mercury/Ford, that the car would be put into ‘limp’ mode or something similar. Any INTELLIGENT thoughts on the ‘check engine’ light being on constantly?? Yes Yes, I know a tuner could be bought, if someone wants to give me $400 for one, I’ll buy it! Not sure I would be totally happy with it!!

I hope SteveTA reads this and can answer, he gave me some advice, not necessarily in support of this switch!!

Thanx, TP Blue 03

[MENINBLK]

In effort to have the TCC lock up later and at my command, I tapped into its wire and mounted a switch on the shifter. Works well. HOWEVER, the ‘check engine’ light is now on constantly. My concern is that after a period of time, set by Mercury/Ford, that the car would be put into ‘limp’ mode or something similar. Any INTELLIGENT thoughts on the ‘check engine’ light being on constantly?? Yes Yes, I know a tuner could be bought, if someone wants to give me $400 for one, I’ll buy it! Not sure I would be totally happy with it!!

I hope SteveTA reads this and can answer, he gave me some advice, not necessarily in support of this switch!!

Thanx, TP Blue 03


Thomas,

Disabling the TCC is a no no...
This is why you got a CEL.

The TCC can lockup in ANY gear the PCM wants it to.
Why would you want to disable it ???

Just use your OD button to disble OD and play with your shifter that way.

[TripleTransAm]

Oh my God....

"Not necessarily..." ?

Thomas, for the amount of trouble (and possibly $$, if you managed to fry something in the PCM) that you've gone to, you'd have been WAY better off by getting a chip to lock out your TCC in all gears except OD.

From what I understand, you tapped into the line that provides power to the TCC and have somehow overridden what the PCM is feeding. From an electrical standpoint, this is bad if:
1) you kept the PCM still connected to the TCC... at some point the TCC output from the PCM may be commanding a certain voltage on the line and the hacked-in switch is holding that line at a certain other voltage... this is bad because you're either in a situation where you're shorting the PCM output to ground, or treating the PCM output as an input. Either way, a VERY BAD THING (TM) to do.
2) whether the PCM is still connected to the TCC or not, the PCM seems to monitor RPM changes across the transmission (definitely the TCC, I believe), probably to detect tranny failure (slipping bands/clutches, busted planetaries, etc). If the TCC is being ordered to lock up and the PCM detects that the RPM difference isn't what it should be, it's most likely gonna panic.

So, yes, I'm reading this, and I'm answering, although I don't know what you want me to say. I thought I gave you sufficient food for thought against hacking into the PCM-tranny links (temperature, etc.)... modern OBD-II PCMs are VERY vigilant to operating characteristics, and unless you change the PCM's opinion on certain scenarios, it's VERY hard to sneak something by it.

I really hope for your sake you haven't fried anything... if you haven't already, I'm fairly certain something may fail in the close future if you keep operating your car with these mods.

[RoyLPita]

As novel an idea it is to do, tapping into the on/off TCC circuit will definitely set a code. Example: my 1st GM LS had an early 4.6 cop car engine with an AOD. The cop car PCM, however, works with the AOD-E. It runs ok for a while, but would drop timing to putt-putt mode intermittently and sometimes display a check engine light. When the codes were taken from the PCM, there were at least 7 (because there was no tranny to monitor). One of those codes was Torque converter clutch failure.

BTW, Lidio's chip doesn't lock up the torque converter until about 63 MPH.

Just my .02 and then some.

[MENINBLK]

BTW, Lidio's chip doesn't lock up the torque converter until about 63 MPH.

Lidio's chip doesn't shift into OD until 63MPH.
The Torque Converter can lockup in any gear.
Most of the time, the PCM will lock it in 2nd, 3rd, and OD.

[RoyLPita]

I beg to differ. Lidio states this in the Alternative Auto chip thread :

"For those of you who drive MM’s and are sensitive to the annoying torque converter lock-up feature employed in the MM trans, I want to emphasize that in our chip for the MM’s… we disable lock-up until its in 4th gear only and just over 62mph."

That is a reason why I would get his chip.

Just my .02 and then some.

[TripleTransAm]

62 mph TCC lockups... damn, that's high. With today's price of gas... :eek:

[MENINBLK]

I beg to differ. Lidio states this in the Alternative Auto chip thread :

"For those of you who drive MM’s and are sensitive to the annoying torque converter lock-up feature employed in the MM trans, I want to emphasize that in our chip for the MM’s… we disable lock-up until its in 4th gear only and just over 62mph."

That is a reason why I would get his chip.

Just my .02 and then some.

This makes no sense.
Disabling the TCC creates more HEAT in the transmission which requires a BIGGER Transmission Oil Cooler.
I hope those of you that are installing this chip are also replacing your cooler with a larger unit.

The transmission is designed to use TCC for less wear and lower temps.
Defeating this purpose is not a smart idea.

I makes more sense to disable OD from kicking in at lower speeds, than to disable the TCC and create more heat.

[TripleTransAm]

The transmission is designed to use TCC for less wear and lower temps.


I think you're on the money with most of your comments, except the above quote...

If you saw the way the stock TCC application was programmed from the factory, you wouldn't be saying the above! :cry:
(I was in a scenario the other day where the tranny was in 4th, and the bloody TCC was at 50% for close to a MINUTE as I plodded along in traffic... and what I thought all along was an application of 3rd gear was actually the TCC engaging at 40-60% from 25kph to 40kph until the real 3rd gear upshift and TCC locked up at 100%).

But, yeah... keeping the TCC off for long periods of time will increase temps through the torque converter slippage.