ECON and PWR light troubleshooting

[magpie]

Hey!

So I made a post a little while ago stating I had some issues after winter storage, with the econ/pwr lights being one of them. Long story short the pwr light stays on when the car is idling, and it never goes back to econ.

I've checked all the vacuum lines for the TVIS switch, they all seem fine. I tried wiggling the connector plug aswell to make sure it's snug.

My concern is that the battery died out during winter so I had to get a new battery. Could it be some electronics was fried when I connected the new battery? Considering all vacuum lines and connections seem fine, could the problem be somewhere in the ECU?

Is there something I've overlooked here?

[Project D]

ECON/PWR light is completely independent of the ECU. it's a vacuum switch on the apron /shock tower.
"83390A"

[banpei]

(06-25-2023 05:27 PM)Project D Wrote:  ECON/PWR light is completely independent of the ECU. it's a vacuum switch on the apron /shock tower.

I took this from the AE86 repair manual:

If it is not functioning as it should in test 1, you replace the bulbs in your dashboard. However, I'm afraid tests 2 or test 3 fail and you will have to replace the switch.

[banpei]

I just took apart the EUDM cluster and found that the ECON and PWR lights are operated by a separate board (called the Econodrive Monitor) attached to the rear of the cluster:

I didn't realize the lights are a little bit more "advanced" than just two bulbs on the cluster. It could be the case your board doesn't function properly or you have a loose contact.

This is the board seen from the other side:


You can test the board without removing it. If you put 12 volts on the E and IG+ terminals (- on E and + on the IG+ terminals) the ECON light should light up. If you then bridge the E terminal and the SW terminal the PWR light should light up. If the board doesn't function fine, check the diodes and the C1213 transistor on the board. Maybe one of them fails in resistance and it will not block the current anymore.

If the board functions fine, you should check the continuity between the switch and pin 13 of your gauge cluster. You can find the pin below, or just follow the SW wire down to the floppy circuit mat and then follow that trace to the connector.

If the continuity is fine, check if the switch works as described above.