Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

700R4 Lockup Identification

Discussion in 'The Garage' started by NerdBoy, Sep 30, 2003.

  1. NerdBoy

    NerdBoy 1/2 ton status

    Joined:
    Dec 24, 2002
    Posts:
    429
    Likes Received:
    0
    Location:
    Southern Illinois
    Ok, I have searched for a bit, and I didn't really find anything on this.
    I bought my K5 right after a new transmission had been put in. It's a 700R4. My truck is an 89, but all the electronics have been removed. I understand that there were a few different ways for the lockup to be triggered throughout the years of production. How do I identify what type of lockup I have, and what type of TC I have?
    I can't say that I have ever felt the lockup kick in sice I bought it.
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

    Joined:
    Aug 28, 2002
    Posts:
    9,097
    Likes Received:
    144
    Location:
    california
    A year would be really helpfull.
     
  3. 88Silverado

    88Silverado 1/2 ton status

    Joined:
    Mar 13, 2003
    Posts:
    2,664
    Likes Received:
    0
    Location:
    Quartz Hill, So. Cal
    The normal lockup is done by the computer.
    Since all electronics have been removed, theres
    lockup kits you can get that can be retrofitted
    so it will lockup in OD /forums/images/graemlins/thumb.gif

    Theres some info here half way down the page on the conversion:
    700r info
     
  4. NerdBoy

    NerdBoy 1/2 ton status

    Joined:
    Dec 24, 2002
    Posts:
    429
    Likes Received:
    0
    Location:
    Southern Illinois
    [ QUOTE ]
    A year would be really helpfull.

    [/ QUOTE ]

    Well, see, that's the problem. I'm not sure how it find out what year the transmission is. I can't even begin to guess. It was a transmission that the previous owner had laying around that was rebuilt right before I bought the truck.

    [ QUOTE ]
    The normal lockup is done by the computer.

    [/ QUOTE ]

    I have read in a couple of places that there was also a hydraulic lockup, and some sort of mechanical.

    I guess what I need to know is if I can drop the pan, or anything (other than yanking the transmission out) to find out what type of harware it has for the lockup.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    Non-ECM vehicles used a small box above the gas pedal to control lockup, with vacuum, VSS, and brake pedal switch being the "sensors" used to govern lock-up.

    Can someone comment as to whether "some" TBI trucks actually did use the ECM to control lockup, or was cruise and lockup still controlled from that box?
     
  6. 88Silverado

    88Silverado 1/2 ton status

    Joined:
    Mar 13, 2003
    Posts:
    2,664
    Likes Received:
    0
    Location:
    Quartz Hill, So. Cal
    The lockup function works either by the ECM or a vacuum switch. Earlier versions without ECM use a vacuum switch connected to ported vacuum. The transmission receives the signal and applies fluid pressure to the clutches in the lock-up converter. The system switches off due to a signal from the brake pedal.

    On others, the ECM determines the best time to lock up the clutch based on data it receives from sensors and switches. First, the VSS mph must be above a certain point before the TCC can be applied. Since the engine should be warm, CTS (Coolant Temperature Sensor) input is considered too. The clutch is supposed to disengage whenever the car is accelerating or decelerating at a particular rate, and the computer gets this info from the TPS (Throttle Position Sensor). On some transmissions, a third or forth gear switch lets the ECM know what gear is currently engaged so it can vary the conditions under which it applies or releases the clutch, but the trans doesn't have to be in high for the clutch to engage (if you see three or four wires coming out of the TCC connector, the transmission has gear select switches).

    Other controls don't go though the computer. One is a normally open third gear switch in series on the battery side of the TCC solenoid. It prevents lockup until third is engaged. Another, found on certain transmissions, is a 4-3 (four speed) or 3-2 (three speed) pulse switch that opens the TCC solenoid circuit momentarily during a downshift. Finally, there's the brake switch. When the driver puts his foot on the stop pedal, the switch opens, which breaks the circuit to the TCC.

    Lockup actually happens simply by applying 12 volts to the lockup solenoid. You can control the lockup with a toggle switch if you delete the computer. Crude, but it will work. For applications that need control over the lockup torque converter without an ECM, I have heard you can use GM P/N 14032087, "Switch" which came in '83-'84 Chevrolet pickups. This is a vacuum operated switch that when wired in line with the lockup solenoid, will only allow current to flow to the solenoid at high vacuum (light throttle).
    Other manufacturers (B&M and BTOD) make kits to make lockup work without the ECM.

    Heres a good link for troubleshooting lockup problems.
    GM Lockup converter troubleshooting
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    Most of thats correct, but as I posted, non-ECM 700R4 trucks (IE non-CA trucks 81-86) used a box over the gas pedal to control lockup, that used all the same "sensors" as the TBI motors except coolant temp to regulate the TCC.

    It wasn't just a simple vacuum and brake switch, or else you'd have ended up locking the TCC at 20MPH.
     
  8. 88Silverado

    88Silverado 1/2 ton status

    Joined:
    Mar 13, 2003
    Posts:
    2,664
    Likes Received:
    0
    Location:
    Quartz Hill, So. Cal
    [ QUOTE ]
    Most of thats correct, but as I posted, non-ECM 700R4 trucks (IE non-CA trucks 81-86) used a box over the gas pedal to control lockup, that used all the same "sensors" as the TBI motors except coolant temp to regulate the TCC.

    [/ QUOTE ]
    Im sorry...mis-read that.

    [ QUOTE ]
    It wasn't just a simple vacuum and brake switch, or else you'd have ended up locking the TCC at 20MPH.

    [/ QUOTE ]
    I stand corrected.
    You can use a vacuum switch, it requires an internal switch to only allow voltage to be applied when in OD even if vacuum is high running in other gears.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    No problem, just wanted to make sure the poster understood the correct options.

    FWIW, the VSS/vac switch/brake switch setup worked great in my '83, and is fairly common in the 'yards. I'd never consider running a toggle switch, as if I'm going to have an automatic, it's going to be automatic. /forums/images/graemlins/smile.gif
     
  10. uglytruk

    uglytruk 1/2 ton status

    Joined:
    Oct 24, 2004
    Posts:
    1,329
    Likes Received:
    0
    Location:
    IN A JUNKYARD, UNDER A TRUCK*N E Rust Belt
    I just typed in "700r4 identification" in Google, and this thread was just a little ways down, interesting...
     

Share This Page