2005 Recently rebuilt the PCM top stops 1/3 of the way down

[Marianne]

Need advice. Rebuilt the PCM and everything was working fine. First time to put the top down, and the motor cones on, the top starts moving but stops after going a third of the way down. I put the top back up and tried again. Same thing but stopped sooner, so I gave up. I don’t know where to bring the car for repair. Is it the PCM, or mechanical or hydraulic?

I called a very good convertible repair guy who says I probably have a hydraulic leak. He says it’s very common and not the PcM because the motor is working. But I’ve been reading here that it can be a faulty PCM repair, or a relay, or so many other things.
Nowhere do I see a hydraulic leak causing the top to stop working in a Thunderbird. Any advice?

I have only talked on the phone and can take the car to the convertible repair guy tomorrow to see what he says. Or should I go to my auto mechanic shop that sent my PCM to be rebuilt.
Any advice please ? Thanks

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[Txgal]

The top on my 2003 would go down by a little way and then stopped, so I talked to the Ford dealer who said they didn’t know anything about it, also my mechanic shop didn’t know how to fix it either. A friend came over and after searching for a while found a separate fuse box for the top, changed the fuses and walla it now works.
You can get to the fuse box through the trunk, it is totally different than the one under the hood or in the trunk. It was hard to find but I would check the fuses. It might be that simple. Good luck.

The cheapest thing to fix are the fuses, I would start there if you haven’t checked the fuses and see if that fixes the problem.

 

[Frankie the Fink]

Hopefully the tech will be sharp enough to be able to bypass the PCM and operate the top motors directly and ensure the mechanism, hydraulics and pivot points are functioning correctly (or not).. The fuses don't make sense to me if the top is partially working unless there is corrosion in the fuse box; they are binary protection devices, they either work or they don't - but sure, check them out anyway.

 

[Marianne]

This fellow is the convertible expert and he is pretty sure it’s a hydraulic leak. But I don’t see any Thunderbird owners saying that was the reason their top wasn’t working. That’s my worry. I don’t want to pay for another guess that doesn’t work.
I’m going there at 8 am so he can take a look.
Thanks for your advice.

 

[DrDISK]

Marianne, please keep us posted on the diagnosis. My bet is on a hydraulic leak - there is not enough hydraulic fluid in the cylinder to complete the top closure.

 

[davea]

My '05 had the same problem, top went up, partially, then same going down. problem was a small leak at the pump fittings. low on fluid. put new metal cylinders in the replace the plastic units.

 

[doug7740]

Need advice. Rebuilt the PCM and everything was working fine. First time to put the top down, and the motor cones on, the top starts moving but stops after going a third of the way down. I put the top back up and tried again. Same thing but stopped sooner, so I gave up. I don’t know where to bring the car for repair. Is it the PCM, or mechanical or hydraulic?

Since you stated that when you attempt to operate the convertible top the motor comes on and the top starts moving but stops after going a third of the way down, tells me that the problem is not with the control modules. The problem is most likely mechanical, or the system is low on hydraulic fluid.

This is how the convertible top operates:

When you press the convertible top switch to lower the top, a ground signal is sent from the switch to the Front Electronic Module. This tells the FEM that you want to lower the roof. The FEM then sends a signal to the Rear Electronic Module telling the REM to lower the convertible top. The REM then grounds the control side of the convertible top lower relay to energize the relay. Once the relay is energized, voltage is sent from the convertible top lower relay to the convertible top motor and the convertible top motor operates.

When you press the convertible top switch to raise the convertible top, a ground signal is sent from the switch to the FEM. This tells the FEM that you want to raise the convertible top. The FEM then sends a signal to the REM telling the REM to raise the convertible top. The REM then grounds the control side of the convertible top raise relay to energize the relay. Once the relay is energized, voltage is sent from the convertible top raise relay to the convertible top motor and the convertible top motor operates.

The hydraulic fluid level motor/reservoir is located under the cloth cover in parcel shelf area behind the seats. To check hydraulic fluid level in the motor/reservoir, here are the steps you will need to take:

1. Unbolt the lower seat belt anchors (T-47 torx bit)
2. Remove the small plastic covers to the upper seat belt anchors
3. Remove the 5 trim panels from the back parcel shelf area. All five are held in with flat metal friction pins. Plastic trim tools work well to pry the pins out. I do not recommend a screwdriver or anything that can scratch the plastic. Remove the two curved corner panels first
4. Unsnap the cloth cover on each side where it hides the carriage linkage and cylinders. Fold these back and clamp to the top liner with a small clamp or binder clips
5. Remove the 7/16” bolt that connects the rear window defroster body ground on the back metal bulkhead under the window on the driver side (don’t drop it!)
6. Unplug the defroster wire connector attached to the same metal bulkhead on the passenger side
7. Pull both wires through the cloth cover and tuck into the same fold clipped to the liner from step 5
8. Starting at one end, unhook the cloth cover from the rear deck trim. These are held in place with plastic tabs in the seam of the cover. There is an open oval in the tab that slips on/off a plastic/rubber head. Pull gently, or pry with a plastic trim tool
9. On each side where the cloth cover meets the carriage hinges, pry the cover back with the trim tool to remove the 3-4 plastic push pins
10. Unbolt the metal backplate – Eight 1/2” bolts total: 2 on each side of the uprights and 4 bolts on the lower deck (peel back the curved carpet). You may need to slacken the seat belt retractors to access the bottom bolts on the sides. Also remove the lower retractor torx bolts (T-47)
11. Unplug the speakers and remove the backplate with the cloth cover attached. Now you can more easily access the top motor/reservoir, hydraulic lines and lift cylinders
12. If you are just checking fluid/bleeding the system, you can leave the motor in place and pry out the rubber plug near the top of the side panel on the driver side of the motor/reservoir. The unit is wrapped in an insulating cover for noise. You may need to pull back the flap to access the fill plug. The plug is an inch long. I used needle nose plyers and went slow so as not to tear it. Once out, use a small squeeze bottle or turkey baster to top up with multipurpose Mercon ATF to the bottom edge of the opening. Place a shop wrap or paper towel to catch fluid that seeps out. Run the top through a full cycle to lower and lift. Leave the rubber plug out while bleeding. Check the fluid level after each full cycle. When no more fluid is needed, and the down/up cycle is smooth, reinsert the rubber plug

doug7740
1955 Thunderbird Blue

 

[Frankie the Fink]

Great info, so it sounds like one can get the motor to operate separately from the FEM/REM electronics downstream from the relays and check out the mechanicals and motors by themselves and split the troubleshooting in half...

 

[doug7740]

Since the convertible top raise and lower relays are in the auxiliary relay box next to the REM and near the hydraulic fluid level motor/reservoir, all you need to do is apply a ground to pin 85 to energize one or the other relays and the top motor is directly engaged, bypassing all the "smart" electronics.

doug7740
1955 Thunderbird Blue

 

[Marianne]

Since you stated that when you attempt to operate the convertible top the motor comes on and the top starts moving but stops after going a third of the way down, tells me that the problem is not with the control modules. The problem is most likely mechanical, or the system is low on hydraulic fluid.

This is how the convertible top operates:

When you press the convertible top switch to lower the top, a ground signal is sent from the switch to the Front Electronic Module. This tells the FEM that you want to lower the roof. The FEM then sends a signal to the Rear Electronic Module telling the REM to lower the convertible top. The REM then grounds the control side of the convertible top lower relay to energize the relay. Once the relay is energized, voltage is sent from the convertible top lower relay to the convertible top motor and the convertible top motor operates.

When you press the convertible top switch to raise the convertible top, a ground signal is sent from the switch to the FEM. This tells the FEM that you want to raise the convertible top. The FEM then sends a signal to the REM telling the REM to raise the convertible top. The REM then grounds the control side of the convertible top raise relay to energize the relay. Once the relay is energized, voltage is sent from the convertible top raise relay to the convertible top motor and the convertible top motor operates.

The hydraulic fluid level motor/reservoir is located under the cloth cover in parcel shelf area behind the seats. To check hydraulic fluid level in the motor/reservoir, here are the steps you will need to take:

1. Unbolt the lower seat belt anchors (T-47 torx bit)
2. Remove the small plastic covers to the upper seat belt anchors
3. Remove the 5 trim panels from the back parcel shelf area. All five are held in with flat metal friction pins. Plastic trim tools work well to pry the pins out. I do not recommend a screwdriver or anything that can scratch the plastic. Remove the two curved corner panels first
4. Unsnap the cloth cover on each side where it hides the carriage linkage and cylinders. Fold these back and clamp to the top liner with a small clamp or binder clips
5. Remove the 7/16” bolt that connects the rear window defroster body ground on the back metal bulkhead under the window on the driver side (don’t drop it!)
6. Unplug the defroster wire connector attached to the same metal bulkhead on the passenger side
7. Pull both wires through the cloth cover and tuck into the same fold clipped to the liner from step 5
8. Starting at one end, unhook the cloth cover from the rear deck trim. These are held in place with plastic tabs in the seam of the cover. There is an open oval in the tab that slips on/off a plastic/rubber head. Pull gently, or pry with a plastic trim tool
9. On each side where the cloth cover meets the carriage hinges, pry the cover back with the trim tool to remove the 3-4 plastic push pins
10. Unbolt the metal backplate – Eight 1/2” bolts total: 2 on each side of the uprights and 4 bolts on the lower deck (peel back the curved carpet). You may need to slacken the seat belt retractors to access the bottom bolts on the sides. Also remove the lower retractor torx bolts (T-47)
11. Unplug the speakers and remove the backplate with the cloth cover attached. Now you can more easily access the top motor/reservoir, hydraulic lines and lift cylinders
12. If you are just checking fluid/bleeding the system, you can leave the motor in place and pry out the rubber plug near the top of the side panel on the driver side of the motor/reservoir. The unit is wrapped in an insulating cover for noise. You may need to pull back the flap to access the fill plug. The plug is an inch long. I used needle nose plyers and went slow so as not to tear it. Once out, use a small squeeze bottle or turkey baster to top up with multipurpose Mercon ATF to the bottom edge of the opening. Place a shop wrap or paper towel to catch fluid that seeps out. Run the top through a full cycle to lower and lift. Leave the rubber plug out while bleeding. Check the fluid level after each full cycle. When no more fluid is needed, and the down/up cycle is smooth, reinsert the rubber plug

doug7740
1955 Thunderbird Blue

View attachment 32953

Doug, You were 100% correct. As always, you gave outstanding advice. Thank you. I was fortunate to have found a great guy who works with convertible tops on all types of cars, but specializes in the older classic convertibles. I brought my Tbird over to his shop and he immediately saw the problem. There is an elastic band that was not performing properly so that the top could go down. In addition, the hydraulic fluid has a minor leak on one side and he prefers doing both sides at the same time. He will give me an estimate for both repairs and for now, he said that I can use the convertible and to gently push it down if it stops midway. The top went up and down a couple of times without a problem, so I should be ok. The hydraulic leak is not a repair I must do now, as it may work fine for months. So it was not any modules but mechanical and a hydraulic leak. I think that's good news, but the hydraulic repair may be expensive.
So my question now is: Can I ask him to just add fluid and see if I can hold off on that repair? I've been spending a fortune on my Tbird these past few months and if I can wait awhile, I would like to. But if you more experienced owners advise me to get it done now, then I will.

 

[Marianne]

Marianne, please keep us posted on the diagnosis. My bet is on a hydraulic leak - there is not enough hydraulic fluid in the cylinder to complete the top closure.

@DrDISK, You were right! At least partly. I responded above to @doug7740, as he gave me a very detailed explanation of the convertible mechanism and he was correct. It is mechanical and a small hydraulic leak. Thanks for responding.

 

[doug7740]

Doug, You were 100% correct. As always, you gave outstanding advice. Thank you. I was fortunate to have found a great guy who works with convertible tops on all types of cars, but specializes in the older classic convertibles. I brought my Tbird over to his shop and he immediately saw the problem. There is an elastic band that was not performing properly so that the top could go down. In addition, the hydraulic fluid has a minor leak on one side and he prefers doing both sides at the same time. He will give me an estimate for both repairs and for now, he said that I can use the convertible and to gently push it down if it stops midway. The top went up and down a couple of times without a problem, so I should be ok. The hydraulic leak is not a repair I must do now, as it may work fine for months. So it was not any modules but mechanical and a hydraulic leak. I think that's good news, but the hydraulic repair may be expensive.
So my question now is: Can I ask him to just add fluid and see if I can hold off on that repair? I've been spending a fortune on my Tbird these past few months and if I can wait awhile, I would like to. But if you more experienced owners advise me to get it done now, then I will.

@Marianne,

The only way your mechanic could tell if there was a slight hydraulic leak was to pull back the cloth cover that hides the hydraulic fluid level motor/reservoir, the hydraulic lines, and the carriage linkage cylinders.



Since the cover is pulled back, I would check and fill the hydraulic fluid level now.

I have done repairs on a few of these convertible tops and have replaced the cylinders individually without any problems.





doug7740
1955 Thunderbird Blue