Do I need to readjust the Tach
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=10157
Printed Date: July 23, 2025 at 4:03 PM
Topic: Do I need to readjust the Tach
Posted By: vsj552001
Subject: Do I need to readjust the Tach
Date Posted: February 27, 2003 at 11:11 AM
During a few cold mornings this year (below -15C/5F) my '99 Corolla didn't start. Does this mean that I have to readjust the tach. It didn't even crank and when I started the car with the key and then used idle mode it stopped after running briefly. After the car warmed up a bit then it was then fine. Does anyone know why? Obviously, this is going to be hard to troubleshoot - I have to wait until it is below -15C and the problem didn't appear each cold morning. Now that the weather is getting around freezing I guess I'll have to wait until next year. I wish I had done some more tests. Some history ... I personally installed a CT-3100 PROSTART starter in the '99 Corolla 2 years. I haven't had any problems until this year after I got my car fixed in January from a car accident. . The mechanics did some body work and replaced the radiator, battery and fuse box. Other than this little problem it works fine. Could it be the battery that is weak in cold weather?
Replies:
Posted By: jrilla
Date Posted: February 27, 2003 at 12:51 PM
TACH ADJUSTMENTS
ProStart systems have two methods of fine-tuning
the Tach signal that is generated from the vehicle,
the first method is manual Tach searching and
setting and the second is automatic Tach searching
and setting. Either method can be used, however an
automatic search is recommended. Tach adjustment
procedures should be done every time a
new unit is installed. This is because the Tach
signal from some ignition systems can sometimes be
too high or too low, thus causing failed starts under
different temperatures.
The procedures for Tach adjustment are as
follows:
1. Hold Hood switch down for 6 seconds.
2. Release pin-switch (Hood switch). Parking
lights should turn ON.
3. With Parking lights ON, immediately press and
release pin-switch again.
4. Parking lights will stay ON for up to 20
seconds. (If not repeat from step 1)
5. With Parking lights ON, press CH3 (TRUNK)
of the transmitter. (Parking lights will flash 1 to
7 times)
6. Start the vehicle using the key.
7. If Parking lights stays ON, then you have
selected an incorrect Tach wire. (Relocate Tach
wire and start from step 1) If Parking lights go
OFF then proceed to the next step.
8. Allow vehicle to reach regular engine idle
speed, then press and release brakes. (Parking
lights will flash appropriate setting, from 1 to 7
flashes)
9. Press CH3 (TRUNK) of the transmitter, to save
setting. (Parking lights will flash one long flash)
NOTE: A manual adjustment should only be
done if the auto setting is not completing the
crank cycle properly in cold weather.
MANUAL TACH SEARCHING AND SETTING
1. Hold the pin-switch (Hood switch) down for 6
seconds.
2. Release pin-switch. Parking lights should turn
ON.
3. With Parking lights ON, immediately press and
release pin-switch again.
4. Parking lights will stay ON for 20 sec. (If not
repeat from step 1)
5. Press CH3 (TRUNK) of remote transmitter at
the same time. (Parking lights will flash 1 to 7
times)
6. Now you can increase or decrease the Tach
settings, depending on your needs.
7. CH1 will decrease the setting, and CH2 will
increase the setting.
8. After proper setting has been reached, press
CH3 (TRUNK) to save setting. (Parking lights
should flash once long.
-------------
J Rilla
Owner/Installer
Posted By: vsj552001
Date Posted: February 27, 2003 at 2:35 PM
J Rilla, I'm assuming from your answer that you think that I should do a "tach adjustment" again and that should solve the problem I described. I guess it couldn't hurt. I guess I'm just trying to understand why it did not start this year when in the previous years it did. Hmm...Perhaps it was colder this year. vsj
Posted By: jrilla
Date Posted: February 27, 2003 at 2:58 PM
I actually just copied and pasted that entire response from the manual. It cant hurt to try.
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J Rilla
Owner/Installer
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