In an earlier thread, Dennis stated:
"I think two quick measurements will tell us whether we should look inside the motor. With the black/white power connector opened up ...

- Resistance of each of the two pins in that connector to the pump body, or an elbow, anything metallic there. Both should be open circuit.

- Resistance between the two pins. Should be very low, a fraction of 1 ohm (about 0.5 ohm if I remember right), but NOT zero. Need a good low-scale digital ohmmeter to see this."

Dennis,
I got .4 ohm resistance between the connector pins, but no flow from either pin to the pump body - resistance stayed at 1.

Does this tell us anything?

 

Stamford,

That's exactly the way a healthy motor should read. Looks to me like whatever is blowing the 40 amp fuse must be external to the motor (if so, that's good news).

I guess we'd have to turn the motor manually through 1 rev. (while watching that 0.4 ohms) to be totally sure (doable if it comes to that), but I think the odds of the source of trouble being inside the pump are now pretty low.

Any chance of damage to the heavy-gauge wiring upstream from that power connector ... or in the connector?


On the road but I'll try to keep up here ...

 

Switch circuit seems okay. Fuse doesn't blow when the pump is disconnected.The only part of the pump I've ever suspected are the solenoids, especially since when I unplug the yellow one, the fuse does not blow. Plug it back in, it blows. Do you know if a solenoid like this could jam the pump or suddenly develop an internal short of its own?

 

Aha! I don't have a wiring diagram with me ... thought the 40 amp fuse protected only the 2-wire circuit to the motor. If solenoids are also on that fuse, then what you described pretty much narrows it down to the yellow solenoid (the one for the rams, not the latch). Easy to damage the solenoid wires/connector; a short here quite possible


Does the wiring diagram show that the solenoids are powered through the same 40 amp fuse as the motor?

 

Yes, it seems they are.

 

Open the solenoids connector please. Check resistance each solenoid. Should be ~ 12 ohms.

 

Will do!

 

Hi Dennis,
Sorry I let this thread go cold. With the weather turning and other things needing attention, I have not done any further troubleshooting, although I did find the solenoids resistance was spot on. If I ever get it sorted out, I'll let you know.
John

 

No worries. At least our weather does not yet rival, say, Rapid City, S.D. It's getting very ugly very early out there.

For when you next get to it ... I rechecked the schematic, and as I read it the 40 amp fuse that is blowing protects only the pump motor, the solenoids being on a different circuit. It's not clear to me from your description (post #3) what conditions have to be met for that fuse to blow .... both pump connected and yellow solenoid connected?

A jumping-off point for next time maybe ...

 

Hi Dennis, I hope you made it through the winter okay. Now that the weather's getting warm again, I am back to trying to figure why my 40 amp fuse is blowing. The windows operate as they should. I get .5 ohms across the pump connector spades and open circuit from the black and white wires to the pump body. 12 ohms on both solenoids. The fuse does not blow when either solenoid is disconnected, but of course the pump does not operate, either. I took the bell casing off the motor and everything looked good to the eye. The motor turned freely by hand. I had hoped the convertible top fairies might have fixed the problem over the winter, but it appears not. Any suggestions, I hope.
Thanks in advance.
John

 

The 40a fuse is only for the pump forward and reverse operation.

 

Yes, it is. That's why it's so puzzling that the motor appears okay but blows the fuse anyway.

 

Hey there, John

Glad to see you survived the winter too. Gawd, it was awful. Your symptoms really are confusing, but let's poke at a few things.

You mentioned that the pump does not run if either solenoid is disconnected. Have you verified this? Reason I ask is that it seems to me the pump should run under such a condition; I don't see how it would "know" if a solenoid were disconnected.

It occurred to me that to be really thorough we should check the resistance across the pump's power wires using both polarities. If you haven't done so, please check it both ways.

We'll sort this thing out ...

 

Hey Dennis, I don't know how I managed to miss this with all the measurements I've taken, but this afternoon I found that when no solenoids are connected, the fuse does not blow and the top does not move. When I connect the blue (latch) solenoid, the fuse does not blow and the top does not move. BUT when I disconnect the blue solenoid and connect the orange one, the fuse blows. Tested it twice and blew two fuses. Both solenoids read about 12 ohms. Both solenoid connectors are open circuit. And yes there is about .5 across the pump connector spades, regardless of polarity. So I guess the roof solenoid is the culprit. Your thoughts?
P.S. How is the pump grounded?

 

Good morning, John.

In the end we may need an exorcism here, but let's keep trying.

I understand that when no solenoids are connected the top does not move, and the fuse does not blow, but ... does the pump run? Is it receiving power?

I assume the top is up and the latch closed through all this, right?

Please try this test ... cross-wire the solenoids: blue connector to the yellow one and vice versa. Test by depressing the roof switch just for an instant. Does the fuse still blow when the yellow solenoid is connected, or is it the blue one now?

Pump grounding: I'll double check this but pretty sure there should be none. The pump/motor casing is mounted on rubber standoffs. For sure the electric motor inside must be ungrounded since its polarity gets switched back and forth. Come to think ... are your hydraulic hoses plastic like the originals, or do they have a metalic jacket?

edit: Also, please check once more the position of the fuse that is blowing. For sure it's the one for the pump motor, right?

 

Curiouser and curiouser. Both solenoids off, no movement, fuse does not blow. Blue connector connected to either blue or orange solenoid (orange connector off), no movement, fuse does not blow. When I cross-connect blue connector with orange solenoid and orange connector on blue, fuse blows. When I disconnect blue connector from blue solenoid, leaving orange attached to orange, the fuse blows. Connect orange connector to blue solenoid, fuse blows. I can hear the relays clicking and tried swapping them for the hell of it, no change. I got the green shower last year and disconnected the hoses from the pump and capped the ports and use the wrench to open and close the latch. Worked fine for a few days, then one morning, no go. I assume the orange connector/solenoid gets a signal via the opened latch to start pumping up the top, could my problem be at the latch? Both solenoid connectors show open circuit across their contacts. Both solenoids 12 ohm.

 

Also, yup, certain of the fuse position, and no, my hoses are original plastic.

 

What is the wire color code for the and orange connectors?

 

The blue connector is green/white and black. The orange one is green/red and black.

 

Hi, John

Nobody said this would be easy, right?

Some clarifications please:

Both solenoids unplugged, you describe "no movement". I get that the top does not move but I need to be clear on whether the pump is running. Is it is, or is it ain't?

Unpacking your description of experiments, I come away with ... the "orange" connector, connected to either solenoid, blows the motor's fuse. The "blue" connector, connected to either solenoid, does not. Correct?

Are you still running "manual latch" ... i.e. with the latch hose ports capped, or have you re-installed the latch hoses?


The big mystery I am stuck on is that the solenoid circuits and the motor circuit are (or should be) completely separate. From the schematics, we would conclude that nothing going on in the solenoid circuits could blow the motor fuse. I'm starting to think we have some sort of wiring fault ... that the schematics do not reflect what's going on in your car. Maybe someone will see something I'm missing.