I've worked on all kinds of cars , for decades,
and have never seen an ECU that needed to be, or was mounted, so it's
insulated from the vehicles body.

totally normal that an ECU with a metal body is screwed right to a metal
part of the car.

On 9/8/2014 10:39 AM, Neil N wrote:
> Hi all. Thanks much for the responses.
>
> Of note, the old Jetta ECU I rplaced, had som serious burns on  a few small
> components
> and a copper ground trace. You can see where this circuit board trace arced
> to the multi pin connector frame; it's likely that electricity jumped
> the 1/4" gap between these two parts as it may be that this frame part
> grounds to the vehicle chassis. Ironically, engine still ran "ok" but has
> always had a mysterious intermittent lack of power )felt like timing
> retarded) with a more recent slight surge under load at higher PRMs.
> New ecu is working fine. Better power, and at last check, 1.5 MPG better
> fuel efficiency.
>
> Go figure.   ;)
>
> True, it was risky, and you've made an important point, but when I saw the
> circuit board burns on the old ECU, swapping ECUs was a no brainer; I
> compare and inspected the new used ECU to old one before installing. Before
> firing up the engine with the new ECU, i made sure the fuel pump primed and
> that the MIL light came on, ignition on, engine off.
>
> Neil.
>
> PS. thinking now, I recall that in the OEM application, the Jetta ECU mount
> bracket may be insulated from the vehicle frame! The way I mounted it in my
> vanagon, this bracket is "grounded" to the vehicle frame.
>
> Is this incorrect?
>
> Hope this post made sense. Am using an iPad mini to compose it. Thanks.
>
> On Friday, September 5, 2014, SDF ( aka ;jim lahey' - Scott ) <
> scottdaniel@turbovans.com> wrote:
>
>> I'll agree with that too ..
>> for welding on the rig....disconnect all batteries and ecu plugs.
>>
>> Don't know if the rig was running fine on the trip before swapping out
>> the ecu ...
>> but if it was..
>> I sorta have this rule when on a trip ...don't work on stuff unless
>> there is a problem .
>>
>
> --
> Neil n
>
> Blog: tubaneil.blogspot.ca
>
> '88 Westy http://tinyurl.com/c8rlw6p
>
> '81 VanaJetta 2.0 "Jaco"  http://tubaneil.googlepages.com/
>
> Vanagon VAG *Gas* inline-VR Engine Swap Group:
>
> http://tinyurl.com/d7gd5ej
>