This is my first post on the forum. I did a search but couldn't find my crazy keep me up at night issue. Ok so I bought a barn find 86 cutlass brougham 307 olds 113k never seen rain. I've put about 500mi on the clock in two years haha. Anyway I cant keep it in lock up at any speed it did stall when stopping and I replaced the lockup solenoid which fixed that issue. But since day one of ownership I've had a issue with it popping out of lock up. I've checked the power to the trans and its good rock solid 12+ volts (except when brake is pushed normal working brake switch). I've had tons of codes that have popped up. Bad o2 or open circuit, tps high and low, even code 41 loss of signal to ICM. I checked the ground to the trans at the wire and the pin f on the adal same results the ground fades and then drop kinda like when you dim a bulb a few times then turn it off. then unlock then pops back on and locks up for a few then back off. I've cleaned the grounds to the ecm (I've not replaced them they looked new) I understand it could be a ground in the ground wires but any advice would be help! Could a bad ecu or prom cause a drop in the ground I'd hate to chop this cherry olds up by adding aftermarket lockup kits or hard wire the 200r4 its got no power the way it is haha. It seems to run great I'd guess all 140 hp. Things I've replaced o2, tps ( dead on voltage) CTS, t-stat (leak at water outlet) trans fluid filter, map sensor, tcc lock up solenoid. I've not replaced the ICM because I feel the code was set by the computer issue ( I could be wrong). I feel like I'm chasing codes that the part is still good at this point every time I reset the a new code pops up. My main issue is the lock up vary annoying when taking it out on a drive any help or direction would be much appreciated!
overdrive issue gm tech help needed!
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06ggex said:
If this is the correct diagram
http://www.oldspower.com/vb/showpost.ph ... stcount=20
It shows that by forcing a lockup by grounding your alcl pin you actually bypass the ECM. That would tell me that it could indeed be a bad driver in your ECM (not prom) but make sure the ground g250 and g251 are in good shape. Unplug your ecm and from the harness side (important) at the ecm connector, check your grounds using a test light connected to 12 volts. In fact you are checking for a strong ground this way as a multimeter doesn't always pick up weak grounds. Make sure you check the strength of your top gear switch as this could have an effect on your solenoid ground via inside the ecm.
Regards
OK so I got all my jumper cables back out. tested the green/white stripe wire at the trans. I probed the wire and checked it with a test light. I have ground at that wire all the time even when it shifts to fourth. I assume that the switch (naturally open or closed) would change signal. But I have full ground even with the ignition switch off key out. so I guess that's not functioning like it should? I've yet to check what u mentioned but I will tonight and let you know. I appreciate your help a lot!
06ggex said:
If you mean that the ground is coming from the ecm, just unplug the connector and see if your ground on the harness side dissapeares...
I am not in front of my PC now, I will check back later, don't get discouraged, when the CCC system works it works well.
Yesterday it took all of three seconds to find an original wiring diagram for your olds, now it looks like the link no longer works and for the life of me I can't find another. Lots of DIY diagrams.
Can you post up a diagram, I am on vacation and really don't want to go to the shop
Can you post up a diagram, I am on vacation and really don't want to go to the shop
So I unplugged the plug on the trans. tested the 4th gear pressure switch it had full ground. Which tells me the switch could be good or bad( normal open or closed not sure my switch type). Vary little ground from the green wire until the key is turned on then the ground is gone. So at this point the switch is bad because it never opens or closes in fourth. I'll keep you posted I'm going to pull the pan tonight remove the switch and order a new one and see how that does.
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