By Bill Bettridge (Billb) on Tuesday, June 26, 2001 - 08:07 am: Edit

I thought I already posted this, but it disappeared; anyway...

I've been on a water proofing binge lately and have been attacking all my underhood electrical connections with silicone dielectric.

Question is when it comes to the ECU - should the battery be disconnected before undoing the computer harness, or does it matter?

By Bill Bettridge (Billb) on Tuesday, June 26, 2001 - 08:09 am: Edit

sorry - did post it twice - bad brain day

By Blue Gill (Bluegill) on Tuesday, June 26, 2001 - 08:34 am: Edit

don't know the answer, Bill, but I'm waiting for someone to post some advice since I'm planning on doing this too...I haven't unplugged my ECU yet for fear of blowing up the Disco if I do it wrong...

By Ron on Tuesday, June 26, 2001 - 08:36 am: Edit

I haven't unplugged my ECU yet for fear of
blowing up the Disco if I do it wrong...


Me too.

I am thinking tupperware

By Ron L on Tuesday, June 26, 2001 - 09:19 am: Edit

Your best bet is to disconnect the battery for a day. This creates what is known as a "Brain Drain". After doing so you may unplug the ECU and go about your business. Before making a battery conection be sure that your ECU is plugged in firmly. Also (i have not been through my disco yet) if any of the mounting hardware slighly resembles a ground point, you will need to duplicate or re-use these points. Keep this in mind when you are trying to figure out how to Water proof it. I have done the Brain Drain hundreds of times when I used to build high performance fuel injected cars. What this does is erase the loop the computer has developed for specific driving patterns/gas/temp etc... One thing I have learned that should also be mentioned here is always disconnect the batrtery when changing out O2 sensors. I have found this out the expensive way when I did work on a celebrities BMW. There is always a potential static charge on the O2 line which if tapped against the exhaust during the removal/installation can cause Extreme financial dismay to the guy doing the work!!!

Reason for the brain drain, when adding new components like Cam/lifters or anything associated with the performance and Air/Fuel ratio, is is very mportant to do this to achieve maximum performance for whatever the modification may be. Also there is a slight charge involved with the ECU that retains memory in the event a car surges during a Jump start etc.

Hope this Helps

Ron

By Jon Williams (Jonw) on Tuesday, June 26, 2001 - 09:27 am: Edit

Speaking of which, does anybody know of a written method for "re-learning" the ECU when it's plugged in after a memory loss? I know most domestic vehicles with OBDII come with it printed in the owner's manual, but I didn't know if Land Rover thought it necessary to inform their owners of a preferred procedure.

By Bill Bettridge (Billb) on Tuesday, June 26, 2001 - 09:37 am: Edit

Ron L - Thanks for the advice. The mounting looks pretty rudimentary with no special ground points - looks like it is held in place by it's plastic cover with plastic fasteners.

Ron - I was probably going to the tupperware route also or something similar. Looks pretty simple to do with a bit of creative silicone RTV sculpting!

By Kyle Van Tassel (Kyle) on Tuesday, June 26, 2001 - 11:40 am: Edit

Unhook the battery and do what ya gotta do. If you have it hooked up while disconnecting/reconnecting the ECU you cause "Spikes" as you wiggle the connector trying to unplug it. These spikes are what cause bad things to happen. You dont have to sit and wait for a day as someone suggested. The time it takes you to get to unplugging it after the battery has been disconnected is fine. The same is true for all the other components on the car. I would like to make an air bag disclaimer though cause after all the ones I have plugged and unplugged they still make me nervous. I am just waiting for them time when there is enough static charge to set the bastard off in my hands right as I am plugging it in.... I hate em!!!!

Kyle

By Bill Bettridge (Billb) on Wednesday, June 27, 2001 - 01:48 am: Edit

thanks for all the input - I also spoke to a shop owner last night who does this kind of thing often on Rovers and other vehicles - apparently the only thing to really be concerned about is having the key in the ignition (ie: no key - no voltage spike) and battery is OK to leave connected.

Thanks

By Kyle Van Tassel (Kyle) on Wednesday, June 27, 2001 - 05:22 am: Edit

Well , no , its not , that is not correct. The ECU has 12V supplied to it at all times in most cases. Yes it has some switched voltage but that aint gonna be what does it. For most of the sensors on the car thats fine , just make sure the key is off. It used to be my living as well Bill....


Kyle