camarosource

Mechanic noticed this plug hanging out of place. It runs along side of my 700r4 transmission. It's a white plug. He says the end of it is broken and won't fit into the transmission plug anymore. He mentioned he thought it was a sensor or something for the locking torque converter?

What is this plug for? He taped up the end of the plug because it was shorting out against the trans. oil pan and was shorting out 3 fuses instantly.

He mentioned that it MAY not be needed and may have been unplugged on purpose when my Shift kit was installed in my 700r4 years ago.

Any thoughts? If this for the torque converter? IS it needed to be plugged in even if I have a shift kit or something?

[Pics]

1. Circle shows plug
2. Circle shows what mechanic believes the plug, plugs into and suspects it to be a torque converter sensor or something? And if so, suspects it's not needing to be plugged in if I have a shift kit?

Thanks

Stevolwevol

I wish I could tell you what it is for. Try a transmission shop you can trust. Does it go into lock up after the engine starts to warm?

calaban

I have that same plug on my IROC disconnected. I have a Haynes manual and have asked around TGO and no one has given me a straight answer.

I have to believe it has to do with the TC lockup though. That's the only thing I can think would need a plug like that on the 700R4's.

My car has a shift kit in it, but I don't think the TC has been changed.

I have also read about, in an auto with lockup converter, people unplugging them so you wouldn't feel a miss as bad. What leads me to that is when I changed plugs and wires there were 3 different plugs and 2 different wires. The ones they couldn't get to easily weren't changed.

Stevolwevol

Does your tranny lock up calaban? I'm gonna have my IROC on a hoist tomorrow for tires, so I will look to see if I have the same wire, and if it is hooked up or not.

calaban

After doing search on TGO the white 4 prong plug on the driver's side of the tranny is for converter lock up. It only locks up when you are under 30% throttle in 4th gear. I don't know if mine locks up. Before I got the car my father in law's company had financed it, and the guy that had it had the engine rebuilt and at least a shift kit put in it. A girl bought it from him and I bought it from her. So I really don't know what has been done to it. I tried to contact the previous owner for a month straight and could never get a hold of him.

I'm going to plug it in when I get it ready and see how it runs with it.

Stevolwevol

When your tranny goes into lockup, you will notice a "shift". While in third gear, and after your engine is warm, after it shifts it will "shift" again. This is your torque converter locking up.

calaban

I don't think so, but am not positive. I've never driven and automatic that felt like it shifted again after it was in high gear.

BigBadLou

That is absolutely correct.

If it is not plugged in, the TC will never go into lock-up and your low highway mileage (and high RPMs) will be a good indication no TC lock.

Stevolwevol

Also it is not good for the torque converter if it doesn't lock up. It will get hot!

ws6transam

You are assuming, and stating an assumption as fact.

However, the difference between a lockup and non-lockup torque converter is just the electric stator clutch & torrington bearing which lock the stator to the impeller. If the clutch is unused, the converter acts like a conventional torque converter. No extra heat is generated that wouldn't otherwise be there in a non-lockup converter. The heat that is generated, is carried away in the transmission fluid, circulated by the pump, and dissipated by convection and the transmission cooler.

IF your transmission is equipped with a lockup converter, and IF you still have the original ECM on-board, then that plug should help low-speed driveability as well as provide better fuel mileage.

Stevolwevol

This is not what I have learned about locking torque converters. If they don't lock up, the will overheat, and go.

ws6transam

Send me an authoritative link showing this, so that I can be re-educated. Otherwise, I respectfully suggest that it's just misinformation and an incorrect assumption.

Lockup converters run in an unlocked condition whenever you are under moderate to heavy load. They are programmed to lock only in light load, cruising conditions. That is when engine heat and stress are at their minimum. If anything, the opposite condition is the one to watch out for: Lockup when under heavy load. Only expensive, high-performance converters are capable of handling large torque with a locked-up clutch. If you lock up the clutch on an OEM converter at wide-open throttle, (such as at the top-end of the track when drag racing) you may risk damaging the stator clutch, especially if you are pushing a nitrous button at the same time!

Stevolwevol

You can suggest what you want, but if you do not allow a 700 to lock up, it will run hotter and shorten the life of the tranny.

my1994z28

If your converter is NOT locking up,it will affect your gas mileage and yes it will shorten the life of your trans and converter..It will run hotter..Trust me I just experienced this with my 4l60e..same as a 700r4.

Stevolwevol

Thank you.