Lockup not engaging

[pacecarta]

that schemat is correct for the BRF

 

[pacecarta]

heres the wiring physical diagram ..bottom left is BRF and shows the two switches for 3 and 4 (part # 75 one face out toward pan , one in side of valvebody toward rear ) .
the turbo buick also uses the brf 3-4 trans switches to drop the timing and to drop the boost using the boost solenoid which changes the solenoid duty based on gear and lowers it in 3rf or 4th resulting in less boost

 

[turbo96max]

What are the switches doing? Sending 12v or stop sending 12v when they hit 3rd or 4th? I want to check the actual wiring while driving to see if they are behaving as expected to eliminate the ecu from being the issue

 

[v6turbo87]

They either send a ground signal or an open signal to thr ECM. There is no 12 volts involved with the switches. A ground is considered a logic "low" to the ECM and an open is considered a logic "high". When you grounded pin F and you got lock up you proved that the TCC solinoid is working and all of the mechanical parts im the tranny are working. It sounds like the ground signal is not being sent from the ECM. If you have a DMV you can monitor pin F for the ground signal from the ECM. Connect one prob to pin F and the other to pin A. It should read an open. Go for a drive and get up to a 60 mph cruise. The meter reading should read a short if the ECM is sending the ground signal. If it doesn't the quad driver in the ECM is probably blown.

 

[gunzandgearz]

Sweet, good to know but I still don't think its right and the reason is because its showing the switch to be normally closed and I have built some of these units and a boat load of 700r4s and 4l60es and pretty much on these circuits its a single wire which means its getting power from the wire and when the circuit gets charged with fluid ,it closes the switch ,and gets its ground thru the valve body. any way if you disconnect the ecm connector and ground that circuit with key on engine off does it click. the reason this is so important is if we can isolate this part of the circuit then weve just determined that this is all good and now the only thing left is ecm or switches. the problem is if we don't do this to a tee were in trouble because I have a hard time believing both of those switches are bad.Bye the way if you want to check the switches hook a meter to the switch wire and when the car shifts into third it will go from 12 volts to o volts.

 

[turbo96max]

They either send a ground signal or an open signal to thr ECM. There is no 12 volts involved with the switches. A ground is considered a logic "low" to the ECM and an open is considered a logic "high". When you grounded pin F and you got lock up you proved that the TCC solinoid is working and all of the mechanical parts im the tranny are working. It sounds like the ground signal is not being sent from the ECM. If you have a DMV you can monitor pin F for the ground signal from the ECM. Connect one prob to pin F and the other to pin A. It should read an open. Go for a drive and get up to a 60 mph cruise. The meter reading should read a short if the ECM is sending the ground signal. If it doesn't the quad driver in the ECM is probably blown.

So the driver is not dependent on any grounds coming from the 3rd and 4th gear pressure switches?

 

[gunzandgearz]

according to that first schematic if its right and the switch not sol. is ground then power is coming from ecm according to schem. that's what its showing ground at switch.

 

[pacecarta]

i wish you'd quit saying "if its right"

last time ... thats the way the brf is

ignoring you and leaving this thread

 

[gunzandgearz]

well good luck turbo96max I was just trying to help you I guess ill sign off for the night before someone else gets butt hurt

 

[gunzandgearz]

oh and one more thing to answer youre question the computer absolutely has to see a signal from switches before it will ground the lock up sol. I will try to help you get thru this. I am old school and thick skinned people like that don't even phase me if he didn't like what he was reading he could have just not read it.

 

[turbo96max]

the mystery may have been solved but at the same time it will mind screw me forever lol ,,,,im left mind boggled bc i just put my computer in my buddies buick and it did not lockup his converter. put his ecm back on and boom got lockup. time to send a message to Bob again ):

just for additional input. i checked some old logs that i took a few months ago when i had non lockup setup and i didnt even have the plug plgged into the transmission. and the powerlogger shows 3rd and 4th gear checked all the time . what this means im not sure, maybe they are normally closed passing voltage and then fail open when in 3rd or 4th... thanks for the help guys, probably gonna be a month or 2 till i get back at it after sending BOB the ecm again.

 

[TurboBob]

got your email, go ahead and send the ecm, its most likely the driver chip.

Bob

 

[pacecarta]

theres no maybe ..they are NC switches (normally closed ) that means in natural state they are closed (to ground) completing the circuit from the ecu.. when active they open and the ecu sees that as engaged. if you unplug the connector you opened the circuit from the ecu and ecu believes its in 3 or 4 gear
its very possible after you had bob fix the ecu you plugged it in with your old trans wiring setup and blew the driver for lockup.. again

try another ecm already and put this thread to rest

 

[turbo96max]

theres no maybe ..they are NC switches (normally closed ) that means in natural state they are closed (to ground) completing the circuit from the ecu.. when active they open and the ecu sees that as engaged. if you unplug the connector you opened the circuit from the ecu and ecu believes its in 3 or 4 gear
its very possible after you had bob fix the ecu you plugged it in with your old trans wiring setup and blew the driver for lockup.. again

try another ecm already and put this thread to rest

Im hoping to man, sorry for the duplicate repetitive questions. I appreciate your senior feedback. i will unpin the switch wires from the harness just to set the 3rd and 4th gear flags on and do that as a final test. bc im still confused at to why the ecm flags the tcc lock withtout flagging 3rd 4th gear . either way it didnt work in my buddies car. I know the wiring atleast now is right as far as power goes. last time the guys fried the ecu bc i had voltage in the A7 pin which shouldnt be the case. now everything looks good

 

[turbo96max]

got your email, go ahead and send the ecm, its most likely the driver chip.

Bob

Thanks for the support Bob, I will be sending it over.