Using the TechnoMotive Gauge & Launch RPM Selectors / Security Procedure

Please read about the TechnoMotive EPROM Modifications before proceeding.

How are the gauges selected?

Since selecting the gauges is simpler than entering the security, we'll start with gauge selection. This section assumes you have already bypassed security properly.

Since we wanted the TechnoMotive EPROM mods to not require the installation of extra lights and switches, we had to stick to using existing equipment on the car. Lucky for us, all DSM factory boost gauges are controlled the ECU. There aren't a lot of choices for an input device, however. About the only two things the ECU can see at all times without any restrictions that the user can change are the idle switch and the throttle position sensor. Well, for our purposes, these are really two different looks at the same data - is the throttle pedal relaxed, or is it being pressed?

Gauge selection
(1st generation)

Okay, what about conflicts? Well, while the engine is running, you have other reasons to use the throttle than to select a gauge. So that's our first restriction - gauges can only be selected while the engine is off.

Other problems? There are really only five distinct positions on the boost gauge, so we are going to be restricted to a choice of five gauges. Believe me, this is pretty reasonable - we'll bet most of the time you'll be running around looking at the oxygen sensor output. We've found it to be the most useful gauge of the five.

How can the pedal select the gauge? You've probably already guessed the answer by now. Every time you tap on the pedal, the boost gauge pointer will advance to the next selection. Whatever gauge is selected when you start the engine will be the gauge that is displayed from that point on. By the way, the ECU will remember your last gauge selection for the next time you fire up the engine. The default after the ECU loses battery power is selection #1 (Oxygen sensor).

What gauge positions correspond to which gauge? Here is a table of the typical setup. You can customize the gauge choices, so your ECU may behave differently.

Boost Gauge Position Gauge Selection Number Typical Gauge
-14 (off scale) 1 Oxygen Sensor (0-1.0 Volts)
-7 2 Advance (-7 = 10 deg, 0 = 20 deg, +7 = 30 deg, etc)
0 3 "Octane" gauge (0-100%, 0 = 50%)
+7 4 Fuel Injector Duty Cycle (0-100%, 0 = 50%)
+14 5 Battery Voltage (-7 = 10V, 0 = 12V, +7 = 14V, etc)

Summary of gauge selection instructions:

  1. Key in, set to ON, but engine not running.
  2. If your ECU has the security option, it must be bypassed before proceeding.
  3. When the boost gauge is pointing to the selection number of the gauge you want to use, you can start the engine.
  4. To advance the boost gauge to your desired selection number, tap the throttle (just a light tap is all that is needed, usually). The gauge will advance once for every tap. Note that the gauge sometimes moves slowly from #1 to #2.

Note: The CE light should not normally be blinking during gauge selection. If you find it blinking, it is clocking out the ECU failure codes.

How are the launch RPMs selected?

This section assumes that you have purchased the Stage III modifications which allow you to select your launch RPMs once the simple clutch-wire installation has been done.

To select the launch RPMs, you should first familiarize yourself with the instructions for selecting the gauges. Even if you didn't buy the gauge option, the method for selecting the launch RPMs is pretty much the same, except that you press the clutch in during selection. The clutch pedal acts as a shift key, of sorts. Below is a table listing the gauge positions and their corresponding launch RPMs. Keep in mind that the five different launch RPMs can be customized, so yours might be different from this list. Like the gauges, the ECU will remember the last launch RPMs you selected. However, the default after power loss is #3 (in this case, 5000 RPM).

Boost Gauge Position Gauge Selection Number Typical Launch RPM
-14 (off scale) 1 4000
-7 2 4500
0 3 5000
+7 4 5500
+14 5 6000

Summary of launch RPM selection instructions:

  1. Key in, set to ON, but engine not running.
  2. If your ECU has the security option, it must be bypassed before proceeding.
  3. Press the clutch pedal in.
  4. When the boost gauge is pointing to the selection number of the gauge you want to use, you can start the engine.
  5. To advance the boost gauge to your desired selection number, tap the throttle (just a light tap is all that is needed, usually). The gauge will advance once for every tap. Note that the gauge sometimes moves slowly from #1 to #2.

How is the security code entered?

The security code is actually a sequence of pedal taps synchronized with a blinking CHECK ENGINE (CE) light. The CE light will blink once per second. When the light shuts off, the ECU will sample the position of the throttle pedal. It will be rated as either down or up, with down equaling a 1. So, if your specified sequence is 100010, your pedal sequence is down-up-up-up-down-up. The first couple times you try this, it is a little tough, but most people get the hang of it within three tries.

This sequence in the example actually goes something like the following.

If you do not enter the security code, the engine will turn over, but will never start. If you enter the code improperly, wait for the light to blink a few additional times, then start the sequence over again.

The security code is "sticky" as long as the ECU doesn't lose power. Even if the engine should stop or stall for some reason, you do not have to re-enter the security code as long as the key is kept in the ON or START position. This will prevent you from having a problem in the middle of an intersection if you kill the engine off the line.

How do I engage valet mode?

This can seem a bit tricky. Remember that it isn't nearly as hard as it first appears. The valet setup relies on the state of the pedals when the ECU clicks off. Ever hear that "click" from the center console about seven seconds after you turn the engine off? That is the ECU power relay shutting off, killing power to the ECU. Right at that point in time, the pedal state is examined and remembered for action upon starting your engine the next time.

When you first turn the key to ON, security mode will show you which of three modes it is currently operating in. The modes and gauge positions can be seen in the table below. Note that in all three modes the CE light will be blinking, allowing you to enter your security code even if the current mode doesn't require the security mode. This is so you can go back to normal security mode.

Normal Security Security Bypass (clutch-launch systems only) Full Valet Mode
Initial Gauge Position
Security Engine will not start without entering security code sequence Engine will start without security sequence Engine will start without security sequence
Rev Limiter Rev limiter behaves normally Rev limiter behaves normally Rev limiter set to 3250 RPM (or your specification)
How to Engage Enter security code, both pedals out when ECU power relay clicks off Enter security code, clutch pedal down when ECU power relay clicks off Enter security code, throttle pedal down when ECU power relay clicks off

After setting a new security mode, you can check to make sure it "took" by turning the key back to ON. The gauge should now indicate the new mode.

What is the purpose of the Security Bypass? Let's say you are at the track, moving your car around a lot. Entering that security code could get really tiresome by the end of the day. If you have the clutch-launch mods, you can temporarily bypass the security code without hitting the valet rev limiter.

In the following example, we will set valet mode, then pretend to be the valet driving the car.

Still confused? Just remember that if you always enter your security code no matter what, your ECU will always start the engine with valet mode cleared.

Note that it is not necessary to start the car to enable or disable valet modes.

It doesn't work, what can I do?

The idle switch is a very common failure

One thing we have noticed after having done quite a few of the ECU mods is that about half the cars out there have idle switch problems. People would plug in their freshly modded ECU and the gauge selections wouldn't work. We traced every single one of these problems down to the idle switch. Here are the problems we have seen so far.

The first two problems cause the idle switch to always be open, even though the throttle plate is closed. Obviously, this will cause bad idling. But this can also cause bad gas mileage because the ECU drops into special fuel saving modes when the idle switch is closed. The third will also cause poor gas mileage - it is as if someone was always pressing down on your throttle a little bit, even when you were stopped. The last problem listed isn't really too bad because the idle switch still tracks the throttle position properly, but the throttle will never open 100% until adjusted properly.

These three idle-sabotaging problems also cause havoc for the security sequence entry and the gauge selection process. Both of these depend on the idle switch. We are especially concerned about the security sequence entry - after all, you wouldn't want to get stranded, not able to start your engine, because your idle switch contacts are dirty.

Look at the above four failure modes. The last one really isn't too bad, because you can simply depress the pedal a little farther to overcome the problem, instead of just tapping the pedal. But in the first three failure modes, we find that the idle switch always seems to fail open. The factory did this by design. If it failed closed, the ECU would think the idle switch closed, therefore also the throttle. This might cause drivability problems. But there are no drivability problems if the ECU thinks throttle is ever-so-slightly cracked open. Besides, this would only affect idle, it would not affect the car when driving down the street. A good failure mode to have.

Security sequence solution

The problem for us is that you can no longer enter the "up" sequences of the security code if the idle switch is stuck open. All is not lost, though, as the Throttle Position Sensor (TPS) also gives us an idea of where the throttle is. So we have added a failover mode. If the ECU finds that the idle switch is open when it first wakes up, it will ignore it during the security sequence (only) and rely solely on the TPS. However, this method requires that you press the pedal all the way down instead of simply tapping down. So if you are finding that the ECU is not taking the security code with simple taps, wait a couple blinks and try the sequence once again with full down presses, and full up releases. Small side effect - if your idle switch really is okay, but you have the throttle depressed when you turn the key to ON, the ECU will go into failover mode. No problem, just press the pedal down farther for the down position when you enter your sequence.

Built-in idle switch diagnostics

The worst part about diagnosing idle switch failures is that the ECU simply does NOT at any time ever check the idle switch for failure. So we have gone the extra mile to include an idle switch and TPS diagnostic tool built right in if you get the security mods. If you don't enter the security code within 60 seconds, the ECU will switch to a mode where the CE turns on when the idle switch is closed and the boost gauge displays the TPS value.

In this mode, with your foot off the throttle, the CE light should be on and the boost gauge should be pointing at -14. Then, as you press on the throttle pedal, the CE light should turn off and the factory boost gauge should slowly increase in value. Note that there is a lot of filtering on the factory boost gauge - it might be slow to track the TPS value - so try to move the pedal slowly for the best results. By the way, the car won't start until you enter the security code, which you can't from the diagnostic. To exit the diagnostic, shut off the ECU and wait for the seven second click before turning the ECU on again.

©1998 TechnoMotive
January 28th, 1998