http://kick-fix.com/ECU/8v-tbi-schematic91to95.jpg



B15 must be at less than 1v kEY on.
the diode on the ECU main board that can blow up is D102
and costs 3 cents.
the diode goes from B15 pin directly to ground.

the purpose of this is to kill the main relay of you unplug the B connector with key on.
i presume a safty feature.
and the diode blocks the MAIN from closing when some numskull connects the battery up backwards ( a good idea no) save destruction of ECU. ( or hot jumping car backwards)
but if you hot wire an ecu this protection is all gone.
and lots of others.............................

 

your ecu maybe good,
or
bad D102
or grounds bad to ECU main ground buss, fully explained on my elec. power pages
or
bad main relay. (swaps with fuel pump relay , note same PN on side of relay , bingo that)


common-failures

 

ok so i say , again. why not fix the hard failure.
why must you ignore that.

the relays are both below the ECU ,
the fuel pump relay has pink wires , you can probe the easy no need to go to ecu.
every wire has 2 ends always probe the easy to reach first.
the fuel pump relay sometimes has a green socket.
the main relay is wired with unique colors. see them?

see pin D above? blue ( B )

pin b9 above is wrong, its only a gross simplification it really goes to DOME fuse.
and is hot 24/7.
b1 and b2 are main power.

since you are having so much difficulty here are some more drawings.
first are the 2 relays actual and more schematics to post

here is my 91, actual photo ,see the green relay and pink wires
main is next door see the blue wires ? back probe main key on and tell votages.

 

next the simplified , schematic, the wires are accurate the connections are accurate
but routing path drawing to be pretty not real.

hint: use the colors wires to ID all relays.

the below factory drawing i maked up had ! and error, i corrected B9 , b9 is ECU memory and is always hot, if battery is connected.
I also show the internal grounds on ECU and D102. as they really are.

http://kick-fix.com/ECU/8v-tbi-schematic91to95.jpg


next my 91 factory drawing.
y =A
G= B

http://kick-fix.com/look/91_geo_tracker_complete_Page_14.jpg

 

do not assume a fuse that looks good is.
i guess youve never had a hair line crack in a fuse.
use an ohmeter to check for zero ohms.
the fuse.
there are 3 way test 2 work ok looking is poor.
sure a melted fuse bad.

volts tests BEST
ohm test 2nd best.
looking weak.

 

review.
key on
the main relay MUST go hot at blue-blk.
if it dont go hot, then the relay is FAILING to Energize. (lets find out why)?

check voltage , at main Black-red it must BE HOT. if not fuse is blown.

check the voltage at black-white of MAIN relay, it must be hot, if not?, the fuse is blown.

last , check the voltage at mAIN relay Blue wire. it must be almost zero or 0.7v is ok. (even 1v is ok)
at this moment we now know what is wrong, after only 4 checks.

what are those checks.?

 

btw hot wiring the ECu will never make the distributor work.

all red arrow leaving ECU are outputs.
all red arrows going in are inputs.
for ecu to power up at least B1 most go HOT.
and at least B1 must be grounded.
if not the ecu has no power.


just two VM readings B1 and B2 and confirmed ECU has no power
the next step is to find out why MAIN relay is dead. it can be a very very simple reason, something profoundly simple.

take the readings and lets find it.

 

plan
get ECU hot
get Distributor making spark
get injectors to FIRE.

not hard, lets do it.

 

Hello Kick.

Thank you alot for your great support.

I have been back at the repair shop, after its normal opening time (I know the owner ) to find out what is wrong and to try some of your suggested tests.

Test 1- ECM POWER AND GROUND CIRCUIT CHECK

- First of all, I have checked all fuses with VM.....(Kick, I told you, I am not an electronic begineer.... ) ...all fuses are perfectly working.

- ECU connected, normally (no hot wiring), I measure these following pin voltages with key ON:

B1 = 0V; B7=0V; B9=0V; B15= +12V (!)

- As B15= +12V, I have checked the GROUND ECU quality. With a long wire
connected directly from the minus battery pole to the VM I have measured the following ECU pin voltages:

B2=0V; B3=0V; B10=0V;

CONCLUSION: As you suggest, it may be dead the D102 diode (nothing visible, but I have to unsolder that and check it).

Test 2 - RELAY CHECK

According to your drawing sent me before, I have checked with key ON the two fuses pin voltages:

Main RELAY (looking from the cable connector side - white connector):

PIN A= +12V; PIN B= 0V; PIN C= +12V; PIN D= +12V;

FP RELAY (looking from the cable connector side - green connector):

PIN A= 0V; PIN B= 0V; PIN C= +12V; PIN D= +12V;


So far I would check the diode D102.....cause I think the rest is ok.

What do you think?

Thanks

Cheers
Eon

 

Hello Kick.

Thank you alot for your great support.

I have been back at the repair shop, after its normal opening time (I know the owner ) to find out what is wrong and to try some of your suggested tests.

Test 1- ECM POWER AND GROUND CIRCUIT CHECK

- First of all, I have checked all fuses with VM.....(Kick, I told you, I am not an electronic beginner.... ) ...all fuses are perfectly working.
please forgive me, but we had many say that and ONLY the fuse pins were rusty. no disrespect just dogmatic troubleshooting..
lots of screaming and beer cans flying....

- ECU connected, normally (no hot wiring), I measure these following pin voltages with key ON:

B1 = 0V; B7=0V; B9=0V; B15= +12V (!)
ok mAIN is off, and B15 is wrong, the diode is blown.
the 12v does tell me the fuse for IG coil is good.
but the B9 is bad and the dome fuse is blown. Dome fuse not needed to start car. but you cant store DTC codes.

- As B15= +12V, I have checked the GROUND ECU quality. With a long wire
connected directly from the minus battery pole to the VM I have measured the following ECU pin voltages:

B2=0V; B3=0V; B10=0V;

CONCLUSION: As you suggest, it may be dead the D102 diode (nothing visible, but I have to unsolder that and check it).

diode bad or traces to it blown(very tiny traces) need photos of
good traces, i have them all.

Test 2 - RELAY CHECK

According to your drawing sent me before, I have checked with key ON the two fuses pin voltages:

Main RELAY (looking from the cable connector side - white connector):
not sure about pin letter.s? i need colors.
PIN A= +12V; PIN B= 0V; PIN C= +12V; PIN D= +12V;
pin A must not be black-blue as pinA shows.
its easier t o say.
A=12v blk -blue
B= 12v white wire.
C= 12v blue -white
D= 1v blue only, and is d1ow yours must be 1v, or d102 is toast





FP RELAY (looking from the cable connector side - green connector):

PIN A= 0V; PIN B= 0V; PIN C= +12V; PIN D= +12V;
i dont know letters.? sorry only colors....
blu-black will be dead. because main is dead.
blk-white will be hot , due to good IGcoil fuse.
pink will be hot, because of above
pink-blk will be dead (pump) even during 3 seconds key on because main is dead.

infact PF checks are useless at this point.




So far I would check the diode D102.....cause I think the rest is ok.

What do you think?

Thanks

Cheers
Eon

conclusions
since you did check ground (key on?) using battery minus lug.
then we know for SURE, that ground is good on ECU.

and that diode D102 is bad
or wires cut at B15
that diode is just 1N4004 , the most common diode on planet earth.

use meter in diode check mode. i sure you know how.
this allows the meter to forward bias diode junctions.
mine will actually allow measuring the barrier voltage.
700mV.

this diode can blow if someone hot wires the main relay
or as one guy did.
remove the lid to relay, and jam metal inside.

dont forget i can photo my partial naked board.

cheers. have macro lens.

 

Hello Kick!
Thanks for your feedback!

As the diode D102 was working perfectly (+0.56 V for direct biasing, and OC in inverse polarization)....then something else were cheating me......

Indeed, it was almost impossible to note it......but the ECU had a blown
small trace on top layer close to the B-connector......which I have fixed now. I have attacched a photo of that.....

As I will have time to go to the repair shop, I will try again the board and
let you know the results....

Cheers!
Eon

 

yes, as noted the diode will never blow before the trace. THANKS for photo, yours added to the ecu h3LL page.
the diode is good for 1 amp, (more with surge)

the trace is like 0.1amp max

acts just like a fuse. just jump it with 24ga wire.
its easy to do fix 5m.

need more help?

this fail is in the 10 ten. IMHO.

 

key is to messure the diode from the pins on ecu and not the diode directly.
it will FAIL.

 

BTW great JOB,
now you can get spark

next stop , sigh post ahead, SPark city

 

no need to throw $300 ECU at it,
not every-time.

put a 1/2 amp SB fuse there.

just in case the MAIN relay has issues.?
id use an inline fuse. off the shelf OTC.

this car was hot wired. or main has a short from battery to coil
or the coil is just plain old fashioned shorted.
check its coil carefully
they never fail but never say never. grin !

 

Hello Kick,
yes I have jumped the small trace with a GAmp wire. So incredible poor
layout PCB design quality this ECU has. For automotive applications I would had expected more design-care....

However, I need to test the ECU....this will be during this week......

Btw....below I have some more questions:

no need to throw $300 ECU at it,
not every-time.

put a 1/2 amp SB fuse there.

On which line shal I have a 1/2 amp fuse?

just in case the MAIN relay has issues.?
id use an inline fuse. off the shelf OTC.

this car was hot wired. or main has a short from battery to coil
or the coil is just plain old fashioned shorted.

I think the repair shop guy, messed-up things before
to call me for help the first time....and the blown trace is an evidence....

check its coil carefully

Shall I simply check the MAIN fuse disconnected coil
between the correct pin of that if there is still continuity with a VM?
Or do you have other suggestions for this test?

they never fail but never say never. grin !

Thanks alot.
Cheers
Eon

 

i bet mech, cant prove it, hot wired the MAIN and blew up your ecu.

but using an ohm meter
remove main.
measure coil. 10 -40 ohms is range of val. can give exact if need be.
using Rx200 range of DVM.

put fuse between B15 in ECU and MAIN.
now more 60's era mech proof. (hot wire kings i call them)

the fuse is not needed if , you fire crazy mech and coil is reading correctly.

the ecu can not be protected 100% from all hot wire events.
how ever some cars 2010 have $3500 ecu that excell at that.

EG: injectors with AI , injector drivers (ecu can see you overload an injector and
then shuts it down. , almost idiot proof those are. (but then comes.....)????
the inputs are alread protected. they have 1 or 2k protection resistors.
but those outputs ARE NOT protected. NO WAY.

never never shunt or short any output of any ECU made on earth.
or any computer.

a 12volt battery with 500cca can blow anything to H3LL ( you can weld with it)
there is no ECU in the world that can protect from that .
only as the book says, "disconnect battery " before servicing EFI"

ECUs are better to day for sure.

 

Sorry Kick,
could you please tell me the MAIN fuse pin wire color to know where is the
coil and where is the switch? Thanks

Cheers
Eon

 

look at another way

that trace is the fuse and saved the very very expensive deeper circuits.

sure DID.

you could replace that jumper with a modern Poly Fuse. biggest you can find. 100ma?
that be the modern way .

and were not invented in 88.(black sheet of paper for Mitsubishi ecu designs?)

they warm up and increase resistance then saves the damage, after that it cools and shorts.
the are really cool technology and are OTC.

 

ahhhh,
if you know where main is , right.? Next to mr, Green socket and has blue wires.....
it has 4 wires.
each is a diff color , pin # varsus by books, and GM and SUZ
but wire color rules
B15 drive. coil.
see relay , now make a drawing of what pins connect to
black-white and the blue pins.
now remove relay

now measure those 2 pins, for ohms zero is bad. 10 to 40 ohms, is ok
if ok
then put a 1/2 amp inline fuse inline of B15 blue
cut wire splice in fuse
or alternately
the jumper in the ecu , that you just put in, could have been, and inline fuse.
this will protect the ecu.

we dont really know who or what caused it but we are suspisious. huh?

how is that. partner.

 

its very close to spark day.
i can tell.

 

Hello Kick!
Thanks alot for your test plan.

Everything clear. :lol:

Test will be done on Thursday as I am on travel for work untill then....

I will let you know results.

Cheers
Eon

 

no hurry.
but that drawing above shows all that must work, to make motor run.
us the colors of the wires.
and win.

 

Hello Kick,
back from my ECU test of this afternoon.

**RELAY Check:

MAIN RELAY:
Refering to the picture you have provided for the "ECM POWER AND GROUND CIRCUIT CHECK", I have routed the wire colors as it follows:

BLK/WHT = C pin = Coil to the "circuit fuse for ignition coil"
BLU = D pin = Coil to ECU B15
BLU/BLK = B pin = To MAIN power
BLK/RED = A pin = FI

COIL resistance = 66,7 Ohm.

FP RELAY:
Refering to the picture you have provided for the "ECM POWER AND GROUND CIRCUIT CHECK", I have routed the wire colors as it follows:

BLK/WHT = C pin = Coil to ECU B13
PNK = D pin = Coil to ECU B16
PNK = B pin = To Fuel Pump
BLU/BLK = A pin = To MAIN power

COIL resistance = 65,9 Ohm

**With 0,5A fuses between B15 and D102, I have tried to start the
car with the following results:

With key-ON:

1) CEL comes ON;
2) MAIN relay closes UP;
3) Measured voltages:

B1 = B7 = B9 = MAIN (+12V)
B15 = +0,8V
All known board pins with +5V have the correct voltage.
The relays does not get mad anymore, and the board seems
healty. However, the car does not start.

POSSIBLE CONCLUSION:

1) As the FP relay seems that it does not get closed (I am not sure if I have to wait 3sec. or not, I have to check it better), what could cause this eventual problem?

2) It could be that sparks does not come as the spark plugs are wet as the long time the car is dead and something on the engine shall be fixed/cleaned back by the repair shop guy. He will check that on Saturday morning.

Menawhile any ideas for extra check?

Thanks alot!

Cheers
Eon

 

Vsig: Suzuki Vitara JLX TBI -1991 - 1.6L -8V manual and 4WD (European - Germany)
ok ECU is alive.
do the CEL codes come out , with diag jumper placed this is always #2 check
code 12, or some others.. not dead.
then next easier an logical is spark

find a spare, any heat spark slug gap it near 28 thou.
then crank it see if #1 wire sparks.

I forgot did you ever check compression. ? (in the swamp, forgot we were draining it. down gator.)

yes, do check CEL diagnostic jumper , insert the paper clip, 4pin plug next to battery.
per my CEL page.
you dont have a NAG, so forget any refr to that malarkey.

CEL DTC code 12?
and spark?\\

it will run, just do the steps.

if you got spark and you think compression is good. and cam is timed.
and spark it timed ? correctly then
1: see if car starts WOT, to dry out wet plugs.
2: if it has spark try test fuel, if dry.
3: if it starts with test fuel?, then check

A: noid light test or
B: fuel pressure which ever is easier. (tools dictate that)

if you even suspect pressure is bad fuel , then do my fast pump page
which includes seeing if the rubber return line on FPreg will piss into a bucket.
coffee can.?

listen for pump to turn of for 3 seconds each key on.
at filler neck if need be. (some pumps are very quiet "bosch"?)

that will keep you going. 1hr. LOL !

cheers.

 

Hello Kick,
I need you could explain patiently in a easy manner what shall I do....see
my questions below (sorry I am not mechanics expert):

Vsig: Suzuki Vitara JLX TBI -1991 - 1.6L -8V manual and 4WD (European - Germany)
ok ECU is alive.
do the CEL codes come out , with diag jumper placed this is always #2 check
code 12, or some others.. not dead.

Do you refer to some CEL codes it is possible to read? How and where?

then next easier an logical is spark

find a spare, any heat spark slug gap it near 28 thou.
then crank it see if #1 wire sparks.

This check will be done by the repair shop guy on sat. morning.

I forgot did you ever check compression. ? (in the swamp, forgot we were draining it. down gator.)

We did last week....of course, then the ECU was still dead or hot wired, so disconnecting the fuel pipe from the INJ plug no fuel was coming out of course....this approach was suggested by the repair shop guy... he will check that again on sat.morning...after I will mount back the ECU....

yes, do check CEL diagnostic jumper , insert the paper clip, 4pin plug next to battery per my CEL page.
you dont have a NAG, so forget any refr to that malarkey.

Could you please explain better what is the check CEL diagnostic jumper and what shall I do?

CEL DTC code 12?
and spark?\\

it will run, just do the steps.

if you got spark and you think compression is good. and cam is timed.
and spark it timed ? correctly then
1: see if car starts WOT, to dry out wet plugs.
2: if it has spark try test fuel, if dry.
3: if it starts with test fuel?, then check

A: noid light test or
B: fuel pressure which ever is easier. (tools dictate that)

if you even suspect pressure is bad fuel , then do my fast pump page
which includes seeing if the rubber return line on FPreg will piss into a bucket.
coffee can.?

listen for pump to turn of for 3 seconds each key on.
at filler neck if need be. (some pumps are very quiet "bosch"?)

Do you have a photo of the precise point I shall place my ear?

Before to check the FP, I shall be sure that the FP relay switch ON to give power to the FP.....and before to transofrm myself in a repair shop guy, I would need to be sure that the the FP relay (which is healty as I check it today), it will be correctly switching as the MAIN one does now......so my question was how to be sure that the FP is correctly driven by the ECU........the rest it will be done by the repair shop guy....as I assume they expected to be also payed for their work so far.....

that will keep you going. 1hr. LOL !

cheers.

Thanks alot.
Cheers
Eon

 

the ear goes to filler neck of fuel filler. cap off (less gas there is the louder , echo box)
wifey poo, KEY on and not crank
bzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzstop after 3sec it does.
each key on repeats (91-98 1.6L only)

see my signature below. see that? one of the first links on my page is cel.

Check Engine Lamp stuck ON?

 

Hello Kick.
Im back from the repair shop.

FP inspection:
I have check the FP noise with key-ON and nothing is produced. The repair shop guy told me (only today), that when intially started to check the car before to call me the first time, the ECU was acting crazy as both MAIN and FP relays were switching all the time (probably due to ECU bad caps), but at that time it was clearly possible to hear the FP switching ON after to switch the key-ON all the times for 3 seconds. Now, this does not happen at all.

CEL error codes:
By the DLC connector (this car has a type 2 with 4 pin plug), only CEL code 12 is flashed all the time.

CONCLUSION:

A) As the pump does not start, there is no compression. We need to check the car together with the repair shop guy, if there are sparks in the spark plug, and if there is fuel compression (I suppose not as no FP noise is produced). This will be done along next week as the repair shop is busy with alot of cars to be fixed.

B) I do not know if the repair shop guy has done something terribly wrong since the first time damaging different car parts.

C) I am getting sick of this car, as all good inspection procedures does not produce some very useful results to get known where is the problem.

QUESTION:

1) After all, if the ECU gives CEL code 12, can we say that the ECU is fully healty? If this answer is YES, then the repair shop guy MUST fix the car, and
I do not need to spend more time down there.

2) Except a damage inside the FP (which I do not believe suddenly happened), what else could cause the FP to not start to create fuel compression? I mean could it be that is still the ECU which is still cheating us
somehow?

Thanks for the help.
Cheers
Eon

 

yes, if the Fuel pump relay does no click on for 3seconds.
i hope when he hot wired it ( i hate that , if careless) he jumpered
power pins to ecu coil side, this blows the ECU fpRELAY driver to kingdom come.
a really dumb act.

please dont get sick yet.we can find all probs. 1 at a time
sadly people make it worse, by hot wiring sh|t theydont understand (60s schools)

no code 12 means
the few things i KNow, are not sorted or open.
but it dont check jack sh|T.

it really is stupid that ecu , it dont even check its own injectors, and many things.
a brick it is.
think of it as a black box.
come on lets fix it.

now then next step , you must prove is the FP relay closing>

way 1
listen to it , i have a stethoscope but screw driver to ear, will allow you to hear it
close for 3sec. each key on.

if mymemory serves (poor) you reported all voltages on the MAIN.
but not the fp relay.

let me stop here are do back reading.