RPMs at 80mph (TCC Problem)

[maybe2fast]

I think there is a problem with the TCC not locking up. I am turning like just below 3 grand. I don't think it is locking up. I adjusted the tcc switch at the brake pedal and I still don't think it is locking.

[2seater]

2500 on my '90 is approx. 90 mph. A '91 with lower gearing should be turning about 235 rpm more at the same speed. 3rd gear, 1:1, would be about 78 mph and change @ 3000 rpm with standard size tires and a 2.97 ratio. You should be able to watch diagnostics and see if it is actually showing the fouth gear signal.

[Reatta1]

I checked mine today. 80 mph on straight and level is 2150 rpm. Just as an aside, each mph changes the rpm by 25, ie; 81 mph is 2175, 82 mph is 2200 etc. 79 mph is 2125, 78 mph is 2100 etc. Hope this helps you.

[maybe2fast]

I have a 90 with the standard 2.97 gearing and I am turning almost 3000 at 80 and it is in fourth gear I just think the TCC is not locking up. thank you for the help fellaz and I will get the scan tool and see if it is locking now that I know the R's should be much lower than I am experiencing.

Don

[VicW]

Why not enter diagnostics and watch the on the ECC for indications of signal to the TCC?

On board diagnostics allow realtime troubleshooting. I do advise having another driver because it is a little distracting to watch for gear indicator and TCC signals while negotiating traffic at highway speeds. This will tell if the various gears are engaging and if the TCC signal is being sent.

Lockup can be subtle and the visual clues can confirm.

When the right conditions are met this transmission will lockup the torque convertor while in 3rd gear as well as 4th or the OD position.

[F14CRAZY]

A 1990 doesn't have the ECC, so diagnostics is harder.

My Reatta today did around 1850 RPMs at about 70, and 80 was like 2250, if I remember right.

[VicW]

In the correct diagnostic mode the Electronic Climate Control will indicate when the trans shifts to each gear and when a signal is sent for TCC. The manual for the 90 discribes the location of indicators.

There is also ECM input modes that will indicate each gear and TCC lockup as well.

[F14CRAZY]

Ah yes, the "Electronic Climate Control." Sorry. I was mixed with "Electronic Control Center."

[maybe2fast]

okay heres the deal, I can manually over ride the TCC with the onboard ECM override. The brake and the TCC switches are adjusted and it still doesn't lock properly (at all).

[VicW]

Does the 'med' light (fan speed indicator) on the ECCP come on while driving in the ECM output mode. Are all the temperature signals working? There will be no lockup below 130 f or in open loop mode.

TCC test procedure has a warm engine off,ignition on. Diagnostic ECM output EO01. result should be a 3 second cycle of hi to lo, also the 'med'will cycle on and off.
If that is functioning, remove and clean the connector at the trans. Check for 12 volts across pin A&D, This will cycle in the test mode also.

Further on check the resistance of the solonoid about 20 ohm by the manual.

I just rolled past 200,000 and rewarded the Reatta with a new trans filter and seven out of eleven quarts of fluid. Then tweaked the vacuum modulator. 1/2 turn CCW at a time. I do not know what giddy-up go juice had been added by others but there is an improvement and it was shifting alright before.

[maybe2fast]

my trans shifts great 1,2,3,4 just no TCC lock up (I will investigate further) like I said I can maually lock it up with the override feature.

[padgett]

Check for proper TPS reading - below 2% and above 50% the TCC will not engage.

[maybe2fast]

So I ran the Reatta down the expressway with the scanner and the coolant was only reading like 130F tops. New t-stat and the TCC works fine, because the motor has to reach 150f before the TCC will engage.

[2seater]

That low temp should have shown up on the gauge? Good news to hear you found the problem, it's useful to all of us.

[maybe2fast]

it would show 4 notches on the gauge where 6 or so is the middle so I thought it was just running at normal. I don't know I should have caught it be I got it fixed. Oh I had heat so I didn't think it was a stat. the heat is much better now...lol

[kennyw]

I was also upset by low tempature readings on my 88 screen when driving in cold weather. 145-165 when really cold in the teens. New t.stat and all. In the summer it runs right up to 185-95. at a loss why as to why the low winter reading on the crt.....car runs fine......go figure......ken

[EDBS0]

Quote:

at a loss why as to why the low winter reading on the crt.....car runs fine......go figure......ken

Simple, you have coolant going around the outside perimeter of the thermostat. The thermostat does not seal completely. Essentially you have a "leak". In the summer it leaks and takes longer to heat up, in the winter it never gets to full operating temperature. Had same problem. It in really cold weather couldn't get over 133. Made a gasket out of duct tape two thickness and cut it just slightly larger than the thermostat. Now runs at 180.