Replacing ECU

[jtgh]

SAVAGE
you need to post car spec.

i do not know if EU and US ECU with same pn are the same.
that is one tough question,

[savage4]

Originally Posted by jtgh

SAVAGE
you need to post car spec.

i do not know if EU and US ECU with same pn are the same.
that is one tough question,

Hi jtgh,

the car specs are:
1993 Geo Tracker
1.6 engine TBI
5 speed manual
2WD

I have changed all caps now and still the same
The pump is using 4.1 amps
But the pump relay and throttle opener solenoid are tikkin.

If I spray a little fuel into the air-intake it starts,and runs normal and the tikkin stops.
As soon as you turn it off, and try to start again the relay goes mad again,
and it won't start.

After replacing the caps I reset the ECU by pulling the "dome" fuse and leaving it out for about 1 minute.
Using the paperclip methode I tried to read the codes but the CEL stays on.

[jtgh]

bad main relay.
same car as mine
look near center of steering column , just above knees.
there are 2 relays side by side on a bracket.
1 is Fuel pump relay green socket
2 other is MAIN. black base socket.

replace main relay,

your problem can be :
1: main relay bad
2: wires bad ( have to add this as many find this here)
3: power over load on main relay out and or ECU.
4: ECU toast.

this problem is reported here 5 times a year.

monitoring all power pins to ECU , can help prove the bad input to ecu.

MAIN is unique, in that the ECU brings it up and then relies on IT (main) to feed power to the ECU so it can boot up. B1 pin at ECU is critical to have clean power.

see attachment. 92-95 8v , very accurate schematic.

No guarantee the relay is bad.
as it could be that the relay is being overloaded at its blue-blk wire.
remove all loads on this wire and see if ecu will come up
and MAIN stops ticking.

[jtgh]

do not assume bad ECU

one person here had a brake lamp wire shorted and a shorted brake lamp switch.

there must not be any shorts on the blue-blk wire, none.
and it goes EVERYWHERE.

cheers.

[jtgh]

try to be clear , exactly what is ticking.
i under stand trottle opener solenoid on top right engine manifold backet clicks
this is the fast cold idle VSV.
and the green socket relay is ticking FP next to main but not main? ticking?

any others ticking?

cheers,

lets find it.

[savage4]

Originally Posted by jtgh

try to be clear , exactly what is ticking.
i under stand trottle opener solenoid on top right engine manifold backet clicks
this is the fast cold idle VSV.
and the green socket relay is ticking FP next to main but not main? ticking?

any others ticking?

cheers,

lets find it.

The problems are the pump relay, the EGR VSV and the IAC elect.
I have already replaced the fuelpump relay and the main relay.
When I take the IAC elect.-conector off , all ticking stops.

hope we can solve it !!
Up till now you have been a great help.

[jtgh]

its shorted , tell me the coil resistance.

i think (IIRC) its 30 ohms.
tell me it.
check coil and coil to ground (case) resistance.

good work , btw.

cheers.

[jtgh]

and when unplugged , it starts?

will take a busy right foot, just apply a tad ,5% throttle.
and it will start and keep it going with foot.
your idle valve will be dead and the attendant loss of air.

cheers.

[savage4]

Originally Posted by jtgh

and when unplugged , it starts?

will take a busy right foot, just apply a tad ,5% throttle.
and it will start and keep it going with foot.
your idle valve will be dead and the attendant loss of air.

cheers.

Hi jtgh,
I just tried it , and if I take off the conector it just won't start.
I also mesured and it's 31.7 ohms.

[jtgh]

hijack 93 8v: relays TICK when IAC is plugged in.


the IAC electric.
if you unplug it , you must add just a tiny bit of air with your right foot , to compensate.
do not floor gas pedal as that is UNFLOOD mode and kills all injection.
just a little more air.

the coil is 31 ohms, did you messure any of the 2 pins to ground with the meter to be sure the coil is not grounded out.
in must read infinity. (open circuit , just like when leads are not touching any thing)

let me get this clear.
the Fuel pump relay clicks if the IAC is plugged in?
that is correct.?

and always starts , with spray can.
and is tuned up too, fresh ign parts end to end.


the problem is
bad power
or bad ECU.

if you have a load on the ECU on its outputs or on the power lines, this is greatly excessive the ECU will fault.
it takes great car to isolate some faults.
id hate to see you replace ECU and then find a chaffed wire.