k20eklipse

I have been told that removing the ECU from your car(security purposes) but not removing the ECU fuse causes your harness to fry..
Is this true ? I'v been wondering about this question for awhile & would like someone to tell me if its true or not
thank you

Former User

To avoid damaging the ECU, disconnect the battery and wait 10 minutes before removing the ECU.

k20eklipse

But i highly doubt someone would want to do that each time they remove their ECU
So your saying without disconnecting the battery, the harness CAN BE DAMAGED ?

Former User

How hard is it to disconnect the battery?

Aside from troubleshooting, anytime you work on electrical components you should disconnect the battery to avoid shorts or voltage spikes that can damage wires and sensitive components like the ECU. Better safe than sorry.

94EG8

I can't say i've ever damaged one or heard tell of it that way, you could theoretically do something to the ECU, harness it self nope. If it means anything i've never disconnected the battery before pulling an ECU and never had any issues.

Jimster480

technically its possible but highly unlikely. I've never heard of anyone damaging an ECU by failing to disconnect the battery first.

k20eklipse

no i dont mean by like working on it
im talking about security purposes, like if you have an alarm & also decide to take out your ecu
you can't disconnect your battery if you have an alarm, then your alarm is useless
i understand what you mean though, before doing electrical work you should always disconnect the battery
i agree with you 100% on that one

Former User

Oh sorry, I misunderstood your question. In your case, you would need to keep the battery connected when you remove the ECU. As you pointed out, I was saying that when you are doing any type of electrical work, you should always disconnect the battery.

k20eklipse

yea i guess i didn't word it correctly, sorry about that
but yea im still wondering if it does fry your ecu ?

Former User

There is a higher risk for ECU damage when it is removed with the battery connected than with the battery disconnected. But based on other comments in this thread, the risk appears to be small.

94EG8

The only thing I will say is that you gas mileage will suffer severely if you pull the ECU out all the time, it takes like 75+ miles for the ECU to complete its learning procedure and mileage in that time frame is pretty poor.

Jimster480

Isnt that only for OBD2 ECU's? Because I don't believe that OBD1 ECU's have memory?

NotAJDMFanBoy

Almost any OBD1 ECU will run any OBD1 motor. I know people who have ran GSR swaps on P28s and such, untuned. Just saying it's not an effective security measure since crooks can and do carry ECUs since this is common.

Leaving the ECU and putting a kill switch in somewhere would be more effective. Or have the real ECU tucked under the dash, and a set of dummy leads hanging so when someone plugs in an ECU...an alarm goes crazy.

94EG8

No, OBD1 has does a drivecycle/learning process as well.

Jimster480

oh. Is it also supposed to remember codes? Because if it does, mine doesnt lol