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Shift Light

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Was just curious if anybody knows how the shift light system is controlled? Mine always lit the very second I let off the clutch. I pulled the bulb and have no want or need for it. I'm more curious than anything about how it works and can the setting be changed so it lights at the correct rpm?

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Here is a the statement from my manual.


Manual transaxle vehicles are equiped with a up-shift indicator lamp. The lamp is normally turned on when the ignition switch is turned "ON", and is turned off when the engine starts.

The lamp will again light during engine operation, according to engine speed and load conditions. A switch, located on the transaxle, prevents lamp from lighting when transmission is shifted to the next highest gear. If the shift of gears is not performed, the ECU will turn the lamp off after 3-5 seconds.


How it senses engine load is the key question. Does the ECU know anything about engine vacuum or is it throttle position and RPM? I thought the switch was just to prevent the light from coming on in the transmissions top gear.

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I'm not sure about jeep, but I know the one in my father's old escort didn't just go on according to RPM, it is based off of that, but it also took in to account %throttle applied, maybe a few other variables, I don't think it's possible to reprogram them.


To follow up, I have had mine come on while I have been in 5th gear :ack:

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