Tip & How-To about Intermatic & Indoor/Outdoor Rain Tight Timer

How to troubleshoot problems with Intermatic Timers T101, T103, T104

This tip was revised on 2/17/11.

Seems more than a few folks are having problems fixing and troubleshooting Intermatic timers, so here are some basic tips that should help. These tips deal with ELECTRICAL PROBLEMS ONLY.

In my experience, with very few exceptions, when these timers start having mechanical problems they need to be replaced.

BE SAFE. _Understand_ that 120 volts CAN kill you under the right conditions.

You will need a Voltmeter such as or similar to this:

This tip is divided into 2 sections:

Section 1 is used if the timer worked correctly at one time, with subsections 1A, (you have power at the timer) and 1B, (you do not have power at the timer).
Section 2 is used if the timer never did work correctly (usually a new installation). You can scroll down to Section 2 now if your timer never did work correctly.


If the timer worked at one time, in this Section 1 we assume that the timer is wired _correctly_. Keep in mind that it is possible that someone may have previously mis-wired the timer while trying to fix it. Incorrect wiring is covered in Section 2.

The first thing one must do is determine if the timer is getting power. A quick check for power is to move the manual lever to the ON position. If the load turns on, you have power. Simple as it seems, this is a CRITICAL step in the troubleshooting process. DO NOT SKIP THIS STEP.

If using a voltmeter instead of the above quick check, you should have the following voltmeter readings:

For the T101: You should have 120 volts measured from terminal #1 to the "A" terminal.

For the T103: You should have 120 volts measured from terminal #1 to the "A" terminal. You must also have 240 volts measured from terminal #1 to terminal #3.
For the T104: You should have 240 volts measured from terminal #1 to terminal #3.

Basically, all we are doing here is checking for proper voltage on the LINE side of the timer. Since the timer clock motor is also connected to these terminals internally, this step also verifies that the timer clock motor is getting the correct voltage.

If you do not have these readings, skip to Section 1B (YOU HAVE NO POWER).
If you have these readings, go to Section 1A.


1...If you have power and the timer does not keep time, the usual problem is that the timer clock motor is bad. Replacement timer clock motors are available. Here's a possible site: http://www.aplussupply.com/intermatic/timer.htm
Make sure you get the correct voltage timer clock motor. The T101 and T103 uses a 120 volt timer clock motor (Cat. # WG1570) and the T104 uses a 240 volt timer motor(Cat. # WG 1573).
If you don't want to mess around replacing the timer motor, as long as the existing timer enclosure is in good shape, you can purchase a new timer and just swap out the guts.

If you have power, but the timer does not keep time, and the load will turn ON using the manual lever or the trippers, the timer is mis-wired. Swap the LINE and LOAD wires.

2...IF YOU HAVE POWER TO THE TIMER AND THE TIMER IS KEEPING TIME, you'll need to check two things:
STEP 1...Are you getting power on the LOAD side of the timer? With the MANUAL LEVER in the "ON" position you should have the following readings:
For the T101: You should have 120 volts measured from terminal #2 to the "A" terminal.
For the T103 and T104: You should have 240 volts measured from terminal #2 to terminal #4.
If you have determined that you have LINE side power and do not obtain the above readings, the contacts on the timer are not making proper contact. Replace the timer guts or install a new timer. If you have the above readings, continue to the STEP 2.
STEP 2...Is the load functional? Go the connection box at the load and see if there is power (remember to turn the timer manual lever to the "ON" position). If you have correct voltage at the load, then the load needs repaired.

3...If there is no power at the load, but there is power on the LOAD side of the timer, then you'll want to ask yourself whether the cable to the load may have been damaged somehow. You'll will also want to check any junction boxes between the timer and the load for bad connections.


IF THERE IS NO POWER, the first thing to do is go to the main power panel and look for a circuit breaker that may be tripped. Look carefully as sometimes a tripped breaker is hard to see. Also remember that to reset a circuit breaker, you need to turn it all the way OFF, then back ON. Even if the breaker isn't tripped, still turn it OFF then back ON a few times (if it is identified correctly) as sometimes that's all it takes to make a breaker work again.

Understand that just because a circuit breaker is turned "ON" does NOT neccessarily mean that it is working correctly. An electrician would simply pull the panel cover and test the terminals on the circuit breaker for the correct voltage. This is the _only_ way to know for sure that the circuit breaker is supplying the correct voltage. It is the first place to start when troubleshooting a no power situation. Proceed with caution. If you are not aware of the hazards involved, by all means call a qualified electrician.

Once you have checked the voltage at the terminals of the circuit breaker, and it is good, then consider that the supply cable may have been damaged or there is a bad connection in a junction box between the circuit breaker and the timer. Has anyone been doing work around the house recently, such as digging or been up in the attic? (depending on how the cable was originally installed)

Also keep in mind that if the neutral connection is bad or nonexistent, you can still have a "hot" wire, but the circuit itself won't work because there is no return on the neutral. This is why you do not want to use one of those no-contact volt testers when troubleshooting electrical problems. When testing for voltage while troubleshooting the only dependable test is between hot and neutral, or in the case of 240 volts, hot to hot.

Sometimes, timers are supplied by GFCI receptacles (the kind with the 2 buttons on them [test and reset] that is usually located in a kitchen, bathroom, or outside). Sometimes these GFCI receptacles are located in very obscure places, so look around for any GFCI's that may be tripped.


Also included here is the possibility that someone trying to fix the timer may have (incorrectly) altered the wiring.
If the timer never did work, the first thing to do is double check that you have power. The next thing to do is double check the wiring. In my opinion, the clarity of Intermatic wiring diagram's leave a little to be desired, so don't feel bad if you mis-read the diagram.

I have already written a tip on how to wire T103's and T104's here:

If you can wire T103's and T104's correctly, you'll have no problem with a T101.
If you have double checked the wiring and there is still a problem, you'll want to follow the steps in SECTION 1 of this tip.


If you have got this far in this tip, you do NOT have an electrical problem with the timer. The problem is mechanical, and as I stated at the beginning of this tip, bite the bullet and replace the complete timer. When the timer is worn to the point where spring mechanisms are not closing the contacts correctly, or the timer stays on because the contacts are welded shut, or gears are jamming, or the trippers are not making contact, chances are pretty good that even if you manage to "fix" it by bending this or that, or spraying the gears with oil, the problem will soon reoccur.

Some mechanical items that are worth checking:
Be sure that the trippers are securely attached to the yellow dial.
Be sure that the yellow dial is pushed in and set to the correct time.

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1 Answer

I have an Intermatic ST01C timer. Works great. I just noticed that I cannot set the DUSK time past 9:11pm. Any minute before that is fine such as 9:10pm but I wanted to set it to about 9:15pm. It has been working fine for about a year and the dusk/dawn is not set to auto. Any ideas b4 I call Intermatic tomorrow? Thanks PC

Call Intermatic.
You can set dawn-dusk parameters a bit longer or shorter than pre-programmed dawn-dusk times.
There is a limit to how many minutes you can add or subtract to pre-programmed times, and I'm not sure how many minutes exactly.
All astronomic timers have limited number of additional minutes, and folks write to fixya occasionally about wanting to extend the limit. But there is no work-around unless you choose to set fixed on-off times instead of using astronomic feature.

If timer begins to malfunction, you reset timer and change CR2 battery, and then reprogram the timer.
Instruction manual has troubleshoot checklist.
Timer comes with 1 year limited warranty.
Open following links for ez instructions, wiring diagrams, and battery illustration:

Jul 29, 2011 | Intermatic Inc. ST01C Digital In-Wall...

1 Answer

i need basic operating instructions how to set timer and how to override the timer

Open following link for T1906 wiring and programming instructions, replacement part numbers, and copy of manual:

Open following link for troubleshoot checklist:

Add a comment for more help.

Upvote the help.
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.

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The green start time is not functioning? I've tried several different green timers and nothing seems to work. Any suggestions?

You posted under Intermatic-malibu power packs
I test timers, I'm not 100% certain what a green timer is.
If you have tried several different green timers, and each has not performed correctly, I suspect electric circuit has interference.
Buy cheap circuit analyzer at home center, and test outlet.
Mover timer to another outlet, on different circuit breaker, and see if problem persists.

For more information on Intermatic/Malibu power packs showing troubleshoot steps, replacement trippers, useful links, warranties and tips:

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The timer wheel turns counter clockwise how can I fix

You posted under Intermatic-malibu power packs.
There are no replacement clock motors.

Improvise by setting timer to override and plug power into cheap plug-in timer.

For information on Intermatic/Malibu power packs showing troubleshoot steps, replacement trippers, useful links, warranties and tips:

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