Where is the ecu ground on a 2002 4sl rodeo

Old post
" ecu wont read bur" ><<<< i can not decode this.
bur, vur,nur, byr,bir, nah, bue, but, ah its BUT? (type analysis, me bad)
ECU won't read ,but fues is good, (test fuse, never just look)
What does wont read mean. by what tool by what actions, by you.?
IF the ECU will not scan with a new scan too the fuses are blown.
period! (or wrong scan tool;) this year is VPW OBD2. (ask)

simple answer, alldata.com RTM.
long answer.
we cant answer on any car lacking engine size (type) and country.
sorry. can't. and be RIGHT.
in uSA its 3 engine this year.
2.2 L I4
3.2 L V6
3.5 L V6 each can be quite different, post engine.

Generics.
horn don't blow can be blown fuse. test them. the one marked HORN being first.
can be bad horn relay or bad clockspring. or even a bad horn
to test any horn, HOT wire it. to any 12vdc battery.

ECU issues, gee, what country and engine and what are the Symptoms of your ECU. in details. running or not.
hot or cold, driving or not.