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connectors by ecu in trunk, undone? what are they?


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what you drive might help out:rolleyes:
ECU in trunk means he's driving an XT or an XT6.

 

Here's a link to the XT/XT6 board: http://xt6.net/forum/

 

The green connectors are for setting the ignition timing. You leave them disconnected unless you're trying to time the ignition. I'm not sure exactly what connecting them does.

 

The black connectors are for reading the stored trouble codes in the ECU. Leave them disconnected also.

 

My XT/XT6 service manual says the following on page 33 of section 2-7:

 

The self-diagnosis function has four modes: U-check mode, Read memory mode, D-check mode and Clear memory mode. Two connectors (Read memory and Test mode) and two lamps Check engine light and O2 monitor) are used. The connectors are for mode selection and the lamps monitor the type of operation.
The Check engine light is in the dash. The O2 monitor light is inside the ECU, visible through a hole in the case. The Read memory connectors are black, the Test mode connectors are green. Both are near the ECU.

 

With the ignition on and both connectors disconnected, the ECU is in U-check mode. This is the normal state. Here's what the manual says about U-check mode:

 

The U-check is a user-oriented mode in which only the MPFI components necessary for start-up and drive are diagnosed. On occurrence of a fault, the warning lamp (Check engine) is lighted to indicate to the user that the dealer's inspection is necessary. The diagnosis of other parts which do not give significant adverse effect to start-up and drive are excluded from this mode in order to avoid unnecessary uneasiness to be taken by the user.
With the ignition on and the Read memory connector connected and the Test mode connector disconnected, the ECU is in Read memory mode. Here's what the manual says about Read memory mode:

 

This mode is used by the dealer to read past problems (even when the vehicle's monitor lamps are off). It is most effective in detecting poor contact or loose connections of connectors, harnesses, etc.
With the ignition on and the Read memory connector disconnected and the Test mode connector connected, the ECU is in D-check mode. Here's what the manual says about D-check mode:

 

This mode is used by the dealer to check the entire MPFI system and detect faulty parts.
With the ignition on, engine running, and both sets of connectors connected, the ECU is in Clear memory mode. Here's what the manual says about Clear memory mode:

 

This mode is used by the dealer to clear the trouble codes from memory after the affected part is repaired.
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Yep, if the ECU is in the trunk, it's of the XT ilk.

 

If you want to pull codes from the ECU, connect the green connectors together, you will be in D-check mode. Drive the car around for a while, and if the Check Engine light isn't on already, it should come on. If it flashes, it has no codes stored. If it stays steady, it has codes.

 

Pop the trunk with the car still running and look at the O2 light on the ECU. It will flash the code at you.

 

This is the experience I've had with my XT anyway, 88 MPFI nonturbo spider intake.

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