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mark corbitt

1987 auto trans won't shift out of 1st

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I mean...there's a list of things to check.

 

Is the Trans fluid full but not overfull?

Is the Trans fluid fresh? (does it look/smell burnt?)

 

All fuses look good?

 

After that, I'd check the wiring to make sure it's all in tact for it.  This is a good resource for what wires to go which shift solenoids.

http://www.radesignsproducts.com/tech.html

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First step -- pull the fuse and see if you can shift manually.

 

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3 hours ago, Eagle said:

First step -- pull the fuse and see if you can shift manually.

 

 

 without tcm shouldnt default to OD?

 

the fact that reverse and OD work means you may have a problem with the speed sensor

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3 hours ago, Eagle said:

First step -- pull the fuse and see if you can shift manually.

 

The transmission fluid level is good, and i had the transmission fully serviced about 6 months ago. What fuse are you talking about?

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11 hours ago, omega_rugal said:

 

 without tcm shouldnt default to OD?

 

the fact that reverse and OD work means you may have a problem with the speed sensor

 

No, not when shifting manually. It should manually shift through the gears. I believe it starts in first and skips second, then you can manually shift to third, and then OD. Either that, or it starts in second and then you can manually shift to third. But the transmission should respond to manual shifting. If it does, then you have an electrical or TCM issue. If it doesn't, then you have a transmission issue.

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11 hours ago, mark corbitt said:

The transmission fluid level is good, and i had the transmission fully serviced about 6 months ago. What fuse are you talking about?

 

The fuse for the TCM (Transmission Control Module).

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On 6/19/2020 at 2:50 AM, Eagle said:

 

No, not when shifting manually. It should manually shift through the gears. I believe it starts in first and skips second, then you can manually shift to third, and then OD. Either that, or it starts in second and then you can manually shift to third. But the transmission should respond to manual shifting. If it does, then you have an electrical or TCM issue. If it doesn't, then you have a transmission issue.

 

he says it goes into first and reverse, he doesnt specify if the shifter is in OD or 1-2, we need to know if it can shift into 2nd and you can't select 2nd manually

 

we need more info

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8 hours ago, omega_rugal said:

 

he says it goes into first and reverse, he doesnt specify if the shifter is in OD or 1-2, we need to know if it can shift into 2nd and you can't select 2nd manually

 

we need more info

 

We do need more information, but you still don't understand how the AW-4 works. Either that, or you're not explaining it correctly. Here's the manual shift diagnosis procedure from the FSM for the AW-4:


MANUAL SHIFTING TEST



NOTE: This test determines if a problem is related to a mechanical or electrical component.

Stop the engine and disconnect the TCU or the TCU fuse.

Road test the vehicle. Shift the transmission manually into each gear range. The transmission should operate as follows:

* lock in Park

* back up in Reverse

* not move in Neutral

* provide first gear only with shift lever in 1-2 position

* operate in third gear only with shift lever in 3 position

* operate in overdrive fourth gear only with shift lever in D position

If the transmission operates as described, proceed to the next step. However, if the forward gear ranges were difficult to distinguish (all feel the same), or the vehicle would not back up, refer to the diagnosis charts. Do not perform the stall or time lag tests.

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i understand how the AW4 works, using only the data the OP provides * 1st gear work but won't shift to second* we can interpret it in diferent ways

 

- we assume he is putting the lever in OD, so the TCU is correctly powering the solenoid AND fluid is going where it should but not getting the speed signal to shift to 2nd

- the transmission IS shifting to 2nd but is not engaging, the OP doesnt say this

- maybe he thinks it´s on 1st gear because it moves but it may actually be stuck on OD

- something is wrong with the TPS that sends WOT to the TCU so it nevers shifts out of 1st 

 

it´s not shifting into 2nd we he can't manually test 2nd gear by disabling the TCU since 2nd gear requires both solenoids on, unless he finds a way to feed 12v to botch solenoids to test 2nd gear we can't pin point the issue

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If you pit the shifter I'm 3 pr D with the TCU unpowered, it will start put in 3rd gear.

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34 minutes ago, omega_rugal said:

i understand how the AW4 works, using only the data the OP provides * 1st gear work but won't shift to second* we can interpret it in diferent ways

 

- we assume he is putting the lever in OD, so the TCU is correctly powering the solenoid AND fluid is going where it should but not getting the speed signal to shift to 2nd

- the transmission IS shifting to 2nd but is not engaging, the OP doesnt say this

- maybe he thinks it´s on 1st gear because it moves but it may actually be stuck on OD

- something is wrong with the TPS that sends WOT to the TCU so it nevers shifts out of 1st 

 

it´s not shifting into 2nd we he can't manually test 2nd gear by disabling the TCU since 2nd gear requires both solenoids on, unless he finds a way to feed 12v to botch solenoids to test 2nd gear we can't pin point the issue

 

The purpose for removing the fuse for the TCU is to determine whether the problem is mechanical (the transmission) or electrical (the TCU, or one or more of the solenoids). If he doesn't run this test, we'll be guessing forever.

 

 

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Thanks so much for everyone's input. When i removed the fuse the transmission seems to shift fine in all forward gears. So i guess this means the TCU is bad? Correction, it does not seem to shift into 2nd, but shifts into 3rd and OD fine.

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If you read the instructions for that test, they tell you it won't shift into second. Did you test the fuse? Is the TCU getting power?

 

You have an '89 -- that has the Power/Comfort switch on the dashboard, right? Have you tried flipping that switch?

 

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Did not test the fuse but on visual inspection it looks fine. It is an 87 but yes it has the power/comfort switch.

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Never go by visual on any fuse, ohms test only. And make sure the blades are clean. Then, use a 12 volt test light to verify you have power before and after the fuse, not on the fuse itself.

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On 6/25/2020 at 4:06 PM, mark corbitt said:

So i guess this means the TCU is bad?

 

the TCU is powering the solenoids as it should, i would test the speed sensor before tossing away a perfectly good TCU, electronics usually fail entirely, a TCU powering up, enabling the solenoids but NOT shifting makes little to no sense, i know electronics, trust me, sounds more like a bad speed sensor or a TPS stuck on WOT

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