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87' Cherokee Laredo Transmission Help

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Old Jul 31, 2012 | 09:50 PM
  #16  
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Originally Posted by 67 GMC
Can you drive with the TCU fuse disconnected? Curious.
Yes, but you'll have to shift 1-2 - 3 by hand and won't have the torque converter lockup.
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Old Aug 1, 2012 | 02:55 PM
  #17  
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Originally Posted by Radi
Yes, but you'll have to shift 1-2 - 3 by hand and won't have the torque converter lockup.
So, no overdrive then. Is it harmful to the trans? With the issues I've been having, I'm worried I'll be on the highway and it will act up and red line. If the TCU is disconnected, the gas mileage will suffer but at least it will be driveable.

Thanks for the reply.
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Old Aug 1, 2012 | 03:58 PM
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Originally Posted by 67 GMC
So, no overdrive then. Is it harmful to the trans? With the issues I've been having, I'm worried I'll be on the highway and it will act up and red line. If the TCU is disconnected, the gas mileage will suffer but at least it will be driveable.

Thanks for the reply.
The trans will also run a bit warmer without the converter lockup so take it easy..
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Old Aug 2, 2012 | 07:27 AM
  #19  
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I think I've hijacked this thread now but the OP sounds like he's happily driving his Jeep which is more than I can say! Haven't put the new TPS in yet as the intermittent shifts fine/doesn't shift at all makes me think of electrical grounds or shorts. This was tucked up under the dash below the glove box. When I got the Jeep, there was a burned and corroded fuse which I replaced with the crimp on connectors. This loop of wire on its own connnector has me stumped. It has infinite resistance (open) and there is 12 V to it. I'm not sure if it was a fusible link that was bad. I'm tempted to just jumper it to see what happens but I thought I would send the pic just in case it's something else.
Attached Thumbnails 87' Cherokee Laredo Transmission Help-img00296-20120802-0817.jpg  
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Old Aug 2, 2012 | 07:58 AM
  #20  
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Do you know that the shift logic ground circuit is at the engine dipstick tube stud?
Have you ever given this Jeep a complete ground refreshing?
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Old Aug 2, 2012 | 09:12 AM
  #21  
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Originally Posted by cruiser54
Do you know that the shift logic ground circuit is at the engine dipstick tube stud?
Have you ever given this Jeep a complete ground refreshing?
I did the dipstick grounds over and cleaned the C101. There's some aftermarket remote car starter installed that I don't have the remote for so another project will be to remove that stuff to avoid more electrical issues.
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Old Aug 2, 2012 | 09:39 AM
  #22  
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I'm pretty sure what you found there is a resistor..200 Ohm? IIRC. I'm not sure. I guess if mine was truly "Open", I'd be looking at the JY for another.

If your 10A fuse and that are toast I'd take a good look at the wiring. No idea if a shift solenoid could do that, maybe.

Last edited by DFlintstone; Aug 9, 2012 at 04:02 PM.
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Old Aug 2, 2012 | 04:16 PM
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Originally Posted by DFlintstone
I'm pretty sure what you found there is a resistor..200 Ohm? IIRC. I'm not sure. I guess it mine was truly "Open", I'd be looking at the JY for another.

If your 10A fuse and that are toast I'd take a good look at the wiring. No idea if a shift solenoid could so that, maybe.
yup. That's where the resistor pack goes. It's 1.2 ohms.
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Old Aug 2, 2012 | 04:43 PM
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Originally Posted by Radi
yup. That's where the resistor pack goes. It's 1.2 ohms.
What happens if you eliminate it? I thought I read somewhere that it worked fine without the resistor, just jumped.
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Old Aug 2, 2012 | 11:14 PM
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Originally Posted by cruiser54
What happens if you eliminate it? I thought I read somewhere that it worked fine without the resistor, just jumped.
It's there to limit current draw in the brake switch/TCC lockup circuit in the event of a fault condition, probably would run fine jumpered.
If there were ever a fault in that circuit, the TCU could be damaged without the resistor to sacrifice itself first. The resistor is supposed to limit current draw until the fuse blows.
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Old Aug 3, 2012 | 07:57 AM
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Originally Posted by Radi
It's there to limit current draw in the brake switch/TCC lockup circuit in the event of a fault condition, probably would run fine jumpered.
If there were ever a fault in that circuit, the TCU could be damaged without the resistor to sacrifice itself first. The resistor is supposed to limit current draw until the fuse blows.

Good to know. Maybe we should be snagging those resistors at the JY?
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Old Aug 3, 2012 | 02:56 PM
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Could someone check their resistor pack for me? Mine is reading about 1200 ohms, not 1.2 ohms. The part number is 83504880 but the description reads 1.2 ohm resistor pack. 1.2Kohms would be 1200.

I cleaned up a lot of wiring yesterday. Separated the fuel injector and sensor wiring and re-ran them through new conduits. There was a ground wire in there that connected to the end of a stud at the rear of the engine near the main braided ground strap. I shined that up as well. The resistance between the sensor ground and the negative battery dropped from 2 ohms to 0.8 ohms so I think that made things better. The trans seems to be shifting ok today but now the engine is stalling a few times at idle which didn't happen before I cleaned up the wiring. I had adjusted the TPS to get the right readings. TPS may be flakey so will replace it once the new one gets here.

Thanks
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Old Aug 3, 2012 | 05:50 PM
  #28  
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Originally Posted by 67 GMC
Could someone check their resistor pack for me? Mine is reading about 1200 ohms, not 1.2 ohms. The part number is 83504880 but the description reads 1.2 ohm resistor pack. 1.2Kohms would be 1200.

I cleaned up a lot of wiring yesterday. Separated the fuel injector and sensor wiring and re-ran them through new conduits. There was a ground wire in there that connected to the end of a stud at the rear of the engine near the main braided ground strap. I shined that up as well. The resistance between the sensor ground and the negative battery dropped from 2 ohms to 0.8 ohms so I think that made things better. The trans seems to be shifting ok today but now the engine is stalling a few times at idle which didn't happen before I cleaned up the wiring. I had adjusted the TPS to get the right readings. TPS may be flakey so will replace it once the new one gets here.

Thanks
Replace the TPS and adjust it now that you have a good ground for it.
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Old Aug 3, 2012 | 06:45 PM
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Originally Posted by cruiser54
Replace the TPS and adjust it now that you have a good ground for it.
Will do. Thanks for your help and your invaluable write-ups.
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Old Aug 3, 2012 | 07:06 PM
  #30  
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Originally Posted by 67 GMC
Will do. Thanks for your help and your invaluable write-ups.
You're welcome. Keep us posted and enjoy your Jeep.
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