solenoid testing

[kevin p]

I'm about to put a used 5R55E auto box in my 1997 Explorer. I'm trying to do as many checks on it before installing.

I want to check all the solenoids are working. Can you simply put 12 volts across the terminals to see if they work, or will this damage them?

Thanks,

Kevin [in the UK]

 

[dogfriend]

You can use voltage across the terminals to see if they work but you must observe polarity. A safer check is to measure resistance of the solenoid.

 

[kevin p]

Thanks for that dogfriend.

I have tested the resistances on the ones thats in the Ex now. They all tested ok, but i'm sure I can remember reading a thread that said just because the resistances are ok doesn't mean they'll actually move when energised.

Do you think it is ok to use 12 volts making sure I get the polarity right?

Will I see them physically move?

Thanks again,

Kev.

 

[budwich]

Its not a polarity issue... is a voltage/current issue.... if you hit it with too much voltage (ie. higher than "rated"), then the current will be higher than normal and you will likely toast the windings... :-(

Having said that most "operating" things on a vehicle are 12v "rated" while sensors are "specialized/regulated" driven (ie. well defined, not "floating" voltage).... for a reason, you want a sensor output to be "accurate" hence you don't want a "varying about 12v" feed, while a relay / solenoid youjust want to operate in any manner you can... and in most cases, the "control" is done by switch in a ground not switching some sort of voltage.

Anyways, enough for the "lesson", from schematics, its appears that the solenoids are fed 12v and the PCM switches in a ground (its normal method) so your test should be fine and is a good one to do for exactly the reason that you state... the resistance of the winding might be OK but the solenoid may not physically / mechanically operate. One warning though is not to leave the solenoid connected / activated for a long period as that might burn out the windings since it is likely that they are "momentary" in normal operation.

 

[dogfriend]

I believe the TCC solenoid uses PWM, but the others are either On or Off.

The instructions in the service manual led me to believe that there may be a polarity issue, but perhaps it is just the wording they chose:

Leave positive lead connected to VPWR solenoid terminal and connect negative lead to the signal terminal of the appropriate solenoid

 

[kevin p]

Thanks very much guys.