No torque converter lockup. No ideA

[GingeRed11]

hey guys. I’ve been posting a lot recently. I just really need to figure this out. I realized that I don’t have any lockup what so ever. My last transmission did, but since I’ve installed this one I don’t recall it ever locking up the converter, this causing 628. I have instinct feeling that it is a transmission issue instead of the pcm sending the wrong signal, because the last one never had this issue. Any ideas? I don’t want to waste money replacing things that aren’t bad. What diagnosis can I perform to pinpoint this issue? 95 4r55e

 

[GingeRed11]

Bump! I replaced the tcc solenoid with no luck. Checked the bolts on the tps and it was fine. Any thing from
Anyone?

Please...

 

[imp]

Bump! I replaced the tcc solenoid with no luck. Checked the bolts on the tps and it was fine. Any thing from
Anyone?

Please...

@GingeRed11
Valve body problem or the clutch itself. To eliminate harness trouble, you could apply 12 volts to the TCC solenoid directly where the wiring enters the transmission case. An audible click should be heard as the solenoid pulls in. If it's heard, the next step would be to determine whether 12 volts applied at or near the PCM to the wire feeding the solenoid will cause it to click. If not, wiring problem, loss of continuity between PCM and transmission. It may be necessary to clip out that one wire to isolate it, and run a new wire to feed the solenoid. imp

 

[GingeRed11]

When I replaced the tcc solenoid. I tested the one that I removed and it was clicking on and off. I have e a feeling that the thing isn’t getting power. Or there isn’t anything left of the clutch. You say it could be the valve body, why? Because the fluid isn’t reaching the solenoid, or not reaching high enough pressure?

 

[imp]

When I replaced the tcc solenoid. I tested the one that I removed and it was clicking on and off. I have e a feeling that the thing isn’t getting power. Or there isn’t anything left of the clutch. You say it could be the valve body, why? Because the fluid isn’t reaching the solenoid, or not reaching high enough pressure?

@GingeRed11
The solenoid opens a tiny passage in the valve body which allows fluid pressure to shift a bigger valve which feeds the clutch apply piston within the TC. Stuck valve in body a possibility. You see, the sophisticated testers used by dealers, even owners having high grade scanners, can "force on" or off, various functions, like the TCC. That avoids having to run the drivetrain in place on stands to see if the PCM commands TCC "on". At this point, I would check wiring continuity between PCM and connector at transmission. To do that, it is almost imperative you have wiring color-codes available. I have those for 1996, not certain they are identical. If you like, I will dig out the wiring book. imp

 

[GingeRed11]

@GingeRed11
The solenoid opens a tiny passage in the valve body which allows fluid pressure to shift a bigger valve which feeds the clutch apply piston within the TC. Stuck valve in body a possibility. You see, the sophisticated testers used by dealers, even owners having high grade scanners, can "force on" or off, various functions, like the TCC. That avoids having to run the drivetrain in place on stands to see if the PCM commands TCC "on". At this point, I would check wiring continuity between PCM and connector at transmission. To do that, it is almost imperative you have wiring color-codes available. I have those for 1996, not certain they are identical. If you like, I will dig out the wiring book. imp

That would be fantastic. I was trying to look it up on the web, with no luck. As long as it’s for the 4r55e and not the 4r70w. Thanks again!

 

[transman304]

If you are chasing the 628 code it is a converter clutch slip code. If the PCM senses a slip over a preset limit in the lock up circuit it will disable lock up function. There are several areas that can be the cause of the detected slip. Damaged sealing ring on the stator, o ring on inner pump gear missing or damaged, lock up clutch itself being worn or damaged, wear on valves and valve body are the first that comes to mind. Some engine controls will inhibit lock up and OD engagement. Coolant temp, MAF, knock.sensor to name a few.

 

[imp]

That would be fantastic. I was trying to look it up on the web, with no luck. As long as it’s for the 4r55e and not the 4r70w. Thanks again!

@GingeRed11
Here ya go, buddy! Hope it helps you. P/Y wire code is Purple with Yellow stripe, from PCM to trans. imp

 

[GingeRed11]

Thanks for the responses! I will have to troubleshoot it Wednesday when I return from vacation. I really hope that it is an electrical rather then hydraulic problem. I don’t want to put too much effort into this transmission. Especially if I have to drop it again. I don’t think I will have time for that. Can I access the pcm -> transmission wires from the engine bay, or from below where it plugs in?

 

[imp]

Thanks for the responses! I will have to troubleshoot it Wednesday when I return from vacation. I really hope that it is an electrical rather then hydraulic problem. I don’t want to put too much effort into this transmission. Especially if I have to drop it again. I don’t think I will have time for that. Can I access the pcm -> transmission wires from the engine bay, or from below where it plugs in?

@GingeRed11
PCM to trans. wiring is contained within the big bundle(s) plugged into the PCM at the firewall. Forget exactly where on Gen 2, but can find out from diagrams if need be. The harness at the PCM connector must have it's tape covering slit, tape unwound, wires separated until those needed are found. Easier at trans., where there are fsar less of them! imp

 

[NCRYPTD]

from post above - "Some engine controls will inhibit lock up and OD engagement. Coolant temp, MAF, knock.sensor to name a few"

I have recently been having unlock and lock repeatedly at times when I see no reason for it such as a hill or such. I have also noticed recently that I think the thermostat is going bad, because now the temp guage shows it is operating below the normal range. Still heats up enough that I get heat from the heater, but it's not quite as much as usual. I had suspected too cold operation might be affecting the lockup because somewhere I remember reading until it reaches normal temp it doesn't do overdrive. Overdrive 4th gear hits, but the lock unlock seems to go in spells. Needs to warm up some and to get the thermostat replaced. I'm hoping will help this problem for me.

 

[974X4BLACKSPORT]

from post above - "Some engine controls will inhibit lock up and OD engagement. Coolant temp, MAF, knock.sensor to name a few"

I have recently been having unlock and lock repeatedly at times when I see no reason for it such as a hill or such. I have also noticed recently that I think the thermostat is going bad, because now the temp guage shows it is operating below the normal range. Still heats up enough that I get heat from the heater, but it's not quite as much as usual. I had suspected too cold operation might be affecting the lockup because somewhere I remember reading until it reaches normal temp it doesn't do overdrive. Overdrive 4th gear hits, but the lock unlock seems to go in spells. Needs to warm up some and to get the thermostat replaced. I'm hoping will help this problem for me.

You are correct, tq. converter lock up is inhibited to expedite engine warm up. Also a thermostat stuck open can also cause the engine to run too cool, delaying tq. conv. lock up, also the ECT sensor also needs to be within good working condition to send the correct value to the ECM/PCM.

 

[NCRYPTD]

I've had the thermostat replaced, and I think my problem with this is fixed. It kinda did it one day, but since then not.