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Discussion Starter · #1 ·
So I have had code 628 for a while. Truck will go for a few days and seem to shift and operate perfectly. Then for no reason, the trans starts shifting very hard.

Looks like it could be the solenoid working intermittently. Before I blow money on the solenoid pack, what can I do to make sure its not the converter itself or another problem in the trans.

I have already checked the wire harness and connectors. That all looked fine.
 

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Satyr of the Midwest
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I did things in a stupid-simple way when the 628 came up: I tapped into the TCC line, and attached a voltmeter between that line and chassis ground.

While driving, I could watch for it to go between zero volts (meaning the PCM was commanding the converter to lock) and battery voltage (meaning the converter should be unlocked). It sounds counterintuitive at first, but that's a matter of perspective, I suppose.

Anyhow, if you see the PCM trying to lock the TCC and nothing happens to the engine speed, or if you can give it a little more throttle and the engine speed rises while it's commanded to lock, then you're assured a problem exists. If there was an electrical problem, then the PCM should also be giving you a code 627 as well. The 628 indicates excessive converter slippage.
 

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Discussion Starter · #3 ·
so at 60+ on the highway in o/d it converter should be locked right?
if so, with the gas held steady, and slight braking added, the rpms should drop right? or maybe slight brake and slight gas to see is rpms go up?
If so its slipping and i gotta problem right?
 

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Satyr of the Midwest
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At a steady cruise, say your 60 mph, if you tap the brake the engine speed should rise slightly, and then come back down as the TCC re-engages. This condition can be intermittent, and it's more of a mechanical problem than an electrical one. The fix for a slipping TCC is to replace the torque converter and stator shaft seal, nothing more. You'd be out a little over a hundred bucks probably, and a few hours' labor, if you get one through a reputable transmission shop. I wouldn't buy anything but an OE-type replacement. You may even be able to get a Motorcraft/Ford replacement through a local dealership, but I've no clue how much their price would be.
 

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Satyr of the Midwest
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If it's been shifting otherwise without a problem, I'd just replace the converter. That's what I did; I had the same code as you, along with some shuddering around 35-40 mph. She's still kicking and shifts better than new, with a shift kit and 188,000 miles. :thumbup


An electrical fault with the TCC circuit or solenoid should result in a 627, but a mechanical fault (slipping converter or leaking stator shaft seal) will usually be a 628.
 

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Discussion Starter · #8 ·
No studdering at all. Drove it 50+ miles today and it drove great. It may drive this way another 5 days and 500 miles. Or I may start it up tomorrow and it will shift hard the first time it changes gears.

I'll get my meter and check the solenoid pack.

I'll also start shopping for a tc. What else should I replace or check if I pull this thing outta the truck?
 

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Satyr of the Midwest
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I agree, but also don't pass up getting a new stator shaft seal from your local Ford parts counter. It's a little piece of Teflon and plastic that looks like a circular piece of jerky, but it's responsible for keeping the hydraulic pressure for the converter clutch contained. I'm fairly certain that's the part that failed on my truck for the PO, burned the converter clutch, and led to its sale to a chebby dealer. All over a stupid piece of plastic that costs about $5.

While the transmission is down, it might be a good thing to check the resistance of each solenoid with a DVOM, or at least document their values. There are five solenoids, IIRC: SS1, SS2, EPC, CCC, and TCC. They should all be similar in value, except for the EPC, which is a variable-force solenoid.
 

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Discussion Starter · #10 ·
If you do the TC, do the front pump seal and the rear main seal.
What sucks is I had the motor out right after I bought the truck. I didn't even have 50 miles on the truck yet. Had i know this problem, it really would have been easier to fix.

I put in a new rear main seal among other things.

I guess I need to invest in the do-hicky that goes on the floor jack so I can strap the trans to it.

I used to have a ford issued book for the E4OD. I gave it to the guy I sold the E4od outta my last truck too. Is there a good online resource for rebuilding this thing?
While Its out, I might as well do everything I can afford to do to it.
 

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I guess I need to invest in the do-hicky that goes on the floor jack so I can strap the trans to it.
That will make your life much easier. Nothing like trying to balance a transmission on a small jack saddle.
 
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