87 740 Jetronic fuel pump relay grounding transistor is bad?'s

  • Thread starter Thread starter Shade\
  • Start date Start date
S

Shade\

Me again.. I discovered that I have two Bosch Jetronics ECU's 0 280 000
544 & 0 280 000 541 who's fuel pump relay's (ecu transistors) will not
energize and make contact. I discovered this by switching a third,
working ECU 0 280 000 511 from my 85 740 to my newly aquired 87 740
turbo and the fuel pump relay energized, made contact and started
without a problem.

I read that there is potentially volvo aftermarketer's or independant's
that sell a kit that allows you to fix the "transistor" problem
onesself. Is anyone knowledgable of this? I called Bergerone Volvo here
in New Orleans and a mechanic acted like he never heard of such a thing.
If not, I am potentially interested in selling, trading, exchanging
these two computers for a good ecu. Also, I read that it's possible to
ground or overide the fuel pump relay. Is anyone knowledgable of this
and if so, could you please elaborate. As well, could someone please
tell me where this transistor is located in the ecu?

BTW: If I manually close the fuel pump relay both ecu's will start and
run the auto. Thanks for any HELP!! :(( SO SAD:((((
 
Shade(y)Tree Mechanic said:
Me again.. I discovered that I have two Bosch Jetronics ECU's 0 280 000
544 & 0 280 000 541 who's fuel pump relay's (ecu transistors) will not
energize and make contact. I discovered this by switching a third,
working ECU 0 280 000 511 from my 85 740 to my newly aquired 87 740
turbo and the fuel pump relay energized, made contact and started
without a problem.

I read that there is potentially volvo aftermarketer's or independant's
that sell a kit that allows you to fix the "transistor" problem
onesself. Is anyone knowledgable of this? I called Bergerone Volvo here
in New Orleans and a mechanic acted like he never heard of such a thing.
If not, I am potentially interested in selling, trading, exchanging
these two computers for a good ecu. Also, I read that it's possible to
ground or overide the fuel pump relay. Is anyone knowledgable of this
and if so, could you please elaborate. As well, could someone please
tell me where this transistor is located in the ecu?

BTW: If I manually close the fuel pump relay both ecu's will start and
run the auto. Thanks for any HELP!! :(( SO SAD:((((
Click to expand...

What you do is take a fuel pump relay from a K-Jetronic car and use it
to turn on your existing fuel pump relay (Volvo pn 3523639), which only
turns the fuel pump on when there is spark. You need to tap into 2
wires at your computer, and run a third to either the ignition coil or
tachometer, and ground 2 more terminals on the new relay.

Connect the following:
Terminal 31 on the new relay to ground. (This is for the circuit inside
the new relay.)
Terminal 30 on the new relay to ground. (This is the current path for
your existing relay.)
Terminal 31b on the new relay to the red-white wire on the coil or
tachometer for engine running signal.
Terminal 15 on the new relay to a switched power wire on your computer
(usually blue or blue-green).
Terminal 87b on the new relay to the black-yellow wire on your
computer. (This is the power path for your existing relay, and the
wire that the computer no longer grounds.)
 
The usual problem is just a cold solder joint in the ECU, worst case is a
blown transistor.
 
You must log in or register to reply here.
Back
Top