How do I check a CTM?

[Dustincoc]

My sister picked up a '96 Mazda B2300 a few months back and has been tryng to get the windshield wipers and speedometer working(amonst other things). Also the temp guage isn't working.

She's been doing some repairs herself, but I was over changing the thermostate today and looked at a few other things while I was at it. She's been replacing the ABS speed sensor on the differential, thinking it was the one that drive the speedo. I showed her where the speedo sensor is located on the output shaft of the transmission. That sensor looks relatively new but she's going to try replacing it.

I've found a schematic and it looks like the next place to check as far as the windshield wipers go is the CTM, which the speedo also seems to run through.

The only info I can find online is how dreaded the repair is and not much else, not even any for sale.

 

[adsm08]

CTM stands for?

 

[Dustincoc]

CTM stands for?

Central timing module...Thats what they chenged the name of the GEM module to in '96.

 

[enjr44]

To me the CTM or GEM is a mystery box!!! It can do weird and strange things.

But, as far as the wipers are concerned, you may get some help here http://www.justanswer.com/ford/44q2g-98-ford-ranger-wipers-dome-light-you-disconnect-module.html

My story. About 18 months ago on my 02 Ranger I was having all sorts of weird problems. Doors locking and unlocking when I moved the key from run to start. Wipers just coming on by them selves (key on, engine off). Everything pointed to the CTM/GEM; but, it was so expensive to replace I decided to just live with it. Anyway the battery in the truck was getting really old, same one it was delivered with, so I decided to change it (truck still started fine, just really old).

Took old battery out and took it with me to get new one. The battery was out of the truck for about 3 hours. Put new battery in and I have never (knock on wood) seen the CTM problem again. Could it have been low voltage from old battery?? Could it have been resetting the CTM by having the battery out of the truck?? I have no clue. Just something to think about/ponder.

Ed

 

[adsm08]

Central timing module...Thats what they chenged the name of the GEM module to in '96.

All my books still call it the GEM.


Anyway, the module is rarely at fault.

 

[6.2]

I have never once heard it referred to as a CTM. Always the GEM.

But anyways. I'm no help here.

 

[Dustincoc]

All my books still call it the GEM.


Anyway, the module is rarely at fault.

Where would you suggest to look? There's power to the wiper motor, the wiper motor is new, all relays have been checkes and double checked. Speedo sensor looks new.

There is a connection problem with the battery, sometimes you need to wiggle the wire to get a connection.

Here's the diagram of the wiper circuit that refers to it as a CTM

 

[bobbywalter]

the wiper motor ground...and all of the grounds along with the connection at the ignition switch.

gem issues i start with good ground and clean power.

 

[adsm08]

^That^

Ford doesn't diagnose modules. They diagnose around the module and then when all else checks out OK assume the module to be bad.

 

[enjr44]

There is a connection problem with the battery, sometimes you need to wiggle the wire to get a connection.

Fix that!!! Without good clean power you are chasing your tail. These things run on computers. Computers do not run correctly on poor/intermittent/crappie power!!!