As to checking, the TPS has a three pin connector. With the key on one end is gound, the other is 5vdc and the center is the value returned to the ECM. with reference to ground, idle should be .37-.45vdc, WOT greater than 4.2 vdc, and my 88 3800 releases the TCC at 53% of the range or around 2.5v. That should be enough to check your setting. I usually just use a scan tool (OTC 2000 - pretty cheap these days) which gives a direct readout of what the ECM is seeing (not always what you read at the TPS).

TPS is a simple device, really just a center tapped potentiometer (variable resistor) so should see a fairly linear output through its range. Places where it drops to zero or suddenly jumps indicate burned spots or shorts and should be replaced.

A lot of the engine parameters depend on the TPS value so must be in good shape.

Personally find it incredible that the trans cooler (or should we call it a "trans heater" ?) would be at the hot end of the radiator. With the stock thermostat that is going to usually exceed 195F. Even my 88 has it on the passenger side (cool end) and I run my cars cooler than normal anyway since live in a hot climate (BTW a 180F thermostat will provide pleanty of heat even below zero F.)

I went out to test my TPS today and i ran into some issues. First i tested the electrical connector. Connecting the A and C terminals on the connector I got a reading of 5v (expected). So far so good.
here'* where i got a problem. I dont know how to test the actual sensor! The only way I get a reading out of my sensor is if I hook up my multi-meter set up to test RESISTANCE (ohms) from A terminal to B terminal. But everywhere i read that I need to check the voltage output of the sensor. Well through measuring resistance I got a measurement of about .8 ohms at closed throttle and at WOT i got a resistance of about 3.9 ohms. I dont know if this is bad or good because i only read about voltage measurements but yet I can't get any voltage readings from the sensor because I have to disconnect its electrical connector to hook up my multi-meter! :?: Am i doing something stupidly wrong? Oh and where on my transmission is that TCC solenoid connector so i can try to unplug it?

Mike D

'87 Bonnie.

If you are reading 5v between a and c then you should read a voltage between b and c (connector must be plugged in and key on).

Am not at home so cannot check for connector location but think it is in front on drivers side (by torque converter).

I'm still off about this connector. When I test A and C for the 5v reading (which i can do ) I first find the TPS, disconnect the electrical connector from it, then take my multimiter to the electrical connector. If I do the same thing only now measure between A and B i get no change in readings when i move the throttle but this is because the connector is unplugged from the actual TPS and it moving obviously wont affect the reading i get from the connector. . . is there some way to keep the connector plugged into the TPS and still be able to tap the connectors with my multimeter?

Mike Diaz

p.*. i think i see the TCC connector but i fear if its not right i coudl damage someting.. any chance of that happening? (i think its right though, its the first connector in the side of the transmission closest to the radiator.)

thanks again you all for all the help!

Oh, and one more thing,

when my TCC engages my engine pretty much locks into about 1000 rpm? on my 'good days' (randomly) it locks into 1500 rpm and feels much better. Which rpms do your engines pretty much stay at once the TCC is engaged?

mike d

Lowest I've seen before was 1300 rpm. Maybe your VSS is acting up since is road speed and gear controlled but then would expect your speedo to be bouncing. The other alternative is a failing ECM but never heard of one affecting only the TCC. What year is your car ?

So,
It seems apparent, that you all are suggesting geting a used tranny from a junk yard.. This seems like a good way to go. Does anyone know roughly how much they would cost? If i found a tranny for my 91, how much would it cost to have my mechanic remove the old and install the new one? also, you mentioned that a trans cooler would help the tranny last longer, are they very expensive? I recenly bought a 96' Bonneville with 98k on it... should i put a tranny cooler in there as well? or would it do no good now...Thanks...

Mine'* an '87. And yes it is strange.. I mean when it'* in its good days and only drops to about 1300 or 1500 rpm at TC lockup it feels more or less like it'* ok and it could be doing what its meant to do but sometimes it goes to the 1300rpm (it might be closer to 1500 but whatever it is its either the 13 or the 15 one of the two.. i'll make sure when i'm in my car next time but i think its about 15or a little below). and then it will stay there for a bit but then after about a minute of being there or a few more minutes of driving it goes from where it is (say 1500rpm with Torque Conv. locked) to the 1000-1100 rpm locked... that'* what confuses me! obviously there are no two possible lockups..

i'm going to try i tomorrow without the TCC plugged in. just hope i pick the right plug !

mike diaz.
'87 bonnie

I would not be too harsh, the only difference between the 440T4 and a 4T60 is a name change in 1990 (and a host of TSBs). True, it is not a THM400 or even a 325 but it was never intended to be.

Also true, the N/A 3800 is the largest engine it was teamed with but you do more damage with a spinning/tramping tire in first than ever in o/d though if you want a low wear example look for one that spent its life behind a 2.8 or 3.1 such as a GP 4-door (non-turbo) - is also more likely to have a 3.33 gear.

Agree the hot end of the radiator is a really dumb place to put the "cooler" but is easily fixed with a external cooler of almost any size though I prefer to keep the entire powertrain cool. Have never needed more than a three core radiator even on 400+ cubes either. Properly tuned there is no need for more.

Personally if it were a car I intended to keep (and our 90 was the last new car we have bought), I'd go for the GM reman in the last non-E version and 3.33 axle but not everyone may feel the same way (can also save a bit by doing the swap myself).

Thanks for the info. I've never had the detent / kickdown cable adjusted (not even sure where/what it is). The car has never stalled out at a stop or while coming to a stop HOWEVER sometimes as I come to a stop I notice that the transmission shifts down awfully late as I get a little kick from it... but its not too often that it happens. Must not be that bad if it'* never caused a stall. I'll keep looking into it but I feel the trans overall is showing its age and should be rebuilt / replaced. Can someone adjust it on their own easily? However so is the rest of the car. I like to fix everything as the problems come up though so that I never have to put it to rest anytime soon.

Mike diaz