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Randall C
Randall C, ASE Certified Technician
Category: Car
Satisfied Customers: 11434
Experience:  32 years Foreign / Domestic Cars All aspects of Diag and Repair
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1995 Isuzu Rodeo: wheel drive 3.2 V6 The battery cables..terminals

Customer Question

1995 Isuzu Rodeo 4-wheel drive 3.2 V6

The battery cables got connected to the wrong terminals. I switched them to the proper terminals and when i turned the key in the ignition only a few warning lights came on. There was no power to the locks, gauges, windows. Nothing would happen when I turn it to the start position. I checked ALL the fuses, the only blown fuse was the Main Fuse(100A). I replaced it and now all the windows, locks and gauges work but the engine won't start. It cranks at normal speed but never attempts to turn over. There is no spark leaving any of the ignition coils. I switched the ECM relay with both the horn relay and fuel pump relay but there was no difference.

I can smell gas when i try starting the engine so i also tried starting it with the fuel pump relay removed just in case it was flooding the engine, that made no difference either.

Not sure what the next step is is diagnosing this mess. Suspect the computer, but unsure how o determine that.
Submitted: 3 years ago.
Category: Car
Expert:  Randall C replied 3 years ago.
Hello, I am Randall .. do you happen to have a testlight to check some things?
Customer: replied 3 years ago.
I have a non-powered one
Expert:  Randall C replied 3 years ago.
Thanks. By non power you mean you can say hook up to the battery and the light will come on when you say probe your battery?
Customer: replied 3 years ago.
yes
Expert:  Randall C replied 3 years ago.
Good. thanks.I need to pull up some diagrams and see what we need to probe. Back very shortly
Expert:  Randall C replied 3 years ago.
Ok, there are plugs going into the coil/ignition module on top of enine. One of the plugs will have a BLACK/ORANGE wire going to the module. I need you to unplg the plug with that wire and turn key to RUN. probe that wire to tell me if it has power to it
Customer: replied 3 years ago.
Ok I did that, the wire does have power when the key is in the RUN position.
Expert:  Randall C replied 3 years ago.
Very sorry for the delay agin. The next thing I will need is the production date of the trck. It will be on the label inside drivers door jam. It will be like 10/1994 or Oct/1994 etc. LMk when you can. If you wish to resume tomorrow lmk or when its best for you. LMk thanks
Customer: replied 3 years ago.
Don't worry about it, I really appreciate your help. The production date is November/ 1995. I'm available all of tonight otherwise tomorrow around noon will work for me. Thanks
Expert:  Randall C replied 3 years ago.
let me gather each thing you will be testing with testlight. I really am hoping not computer so.. I want to be 100% sure we have ruled out any power supply etc.. I will get the info and send later this evening or first in Am so you can doo all tests at one time around noon tomorrow.
Expert:  Randall C replied 3 years ago.
Your ecm should be under the center of the dash. I need you to locate and unplug both plugs from Ecm. test these wire colors in both plugs as shown below. The test is done with key ON, engine NOT cranking , just key in RUN/ON. You should have power on each of these.

SMALL PLUG:

Red/white wire
Red/green wire x2


LARGE PLUG:

Red/white wire
Blue /green wire
Pink/white wire

Unsure when I will be back but should be early afternoon. LMk thanks

Locations
hn95passp_sm6e1-097a



 

Customer: replied 3 years ago.

I'm having trouble with the wire colors. On the small plug there are two WHITE wires with RED stripes(A2 and A7), but no RED wires with WHITE stripes. There is also only one red/green(A6), there is not a second one. On the large plug the only wire with red is a solid red(C2). I could not find a blue/green wire either. The pink/white(C3) wire has NO power.

 

The wires that DID have power were:

Small plug- purple(A5)

red/green(A6)

white/red(A7)

white/green(A8)

brown(A9)

white/black(B1)

 

Large plug- red(C2)

blue/yellow(C11)

blue/white(C14)

white/black(C16)

blue/black(D15)

blue/black(D16)

 

Sorry, I hope I didn't confuse you too much.

Expert:  Randall C replied 3 years ago.
let me check a few things, back shortly
Expert:  Randall C replied 3 years ago.
OK, check these for 12 volt power

B1= white black
C-16= white/black
A6= red/green
C3 = Pink/white ( need to check this wire while cycling key from off the run, back and forth)
Customer: replied 3 years ago.
Every wire has power except pink/white(C3). I went from OFF to RUN back to OFF a few times but it never had power. That's to the fuel pump relay right?
Expert:  Randall C replied 3 years ago.
yes it is. Now,,did you have plugs out or were you back probing the connectors?
Customer: replied 3 years ago.
It was unplugged but i just tested it with both of the connectors plugged back in. There is now power at the pink/white wire when i turn it from OFF to RUN.
Expert:  Randall C replied 3 years ago.
If you can get to any injector plug, do you know how to perform injector pulse test with a testlight?
Customer: replied 3 years ago.
i'm not too sure which wires to probe but i can reach one of the injector plugs.
Expert:  Randall C replied 3 years ago.
Not the easiest test but it is a test we need to do. If you can unplug any injector. Insert say a paperclip in either terminal Does not matter which one. Clamp the testlight clamp lead to the paper clip and then use the probe in the OTHER terminal while CRANKING. I need to know if testlight blinks.
Customer: replied 3 years ago.
The injector is getting power when the engine is cranking.
Expert:  Randall C replied 3 years ago.
so light is blinking?
Customer: replied 3 years ago.
yes, it pulses when the engine is being cranked.
Expert:  Randall C replied 3 years ago.
So far all tests have passed. You say you are 100% sure there is no spark. we know you have fule, injector pulse, power to ECM where needed so we are now down to no spark? how are you testing for spark?
Customer: replied 3 years ago.
i have an in-line tester that connects to either the spark plug and plug wire or the plug wire and ignition coil. I crank the engine but the tester never lights up. I've tried it on different cylinders and all 3 coil packs.
Expert:  Randall C replied 3 years ago.
Thanks. I am on your side. Do not want to say bad computer just yet. Thus why I have you checking everything. Let me see what the flowchart say for just no spark. back shortly
Expert:  Randall C replied 3 years ago.
If you have a tach on the dash, when you crank engine and hold it cranking, can you see the tach needle move at all even if slighlty/
Customer: replied 3 years ago.
wow, I never even realized that. It doesn't even move when the engine is cranking.
Expert:  Randall C replied 3 years ago.
Do you have an Ohm meter?
Customer: replied 3 years ago.
yes, it's a multimeter
Expert:  Randall C replied 3 years ago.
Go to ignition module.

Unplug the connector with three terminals. It will have a white and white.red wires going to it. Maybe a black wire as well.

Set the meter to 2000 ohms (2k) and probe the white and the white/red at the connector. LMk what reading you get
Customer: replied 3 years ago.
it's at 800 ohms
Expert:  Randall C replied 3 years ago.
Your just not going to make this easy are you :) the specs should be(NNN) NNN-NNNN 800? wow that close.This is the crank sensor. Now, what next? well, we need a scanner hooked up to view the cranking signal from the crank sensor. In most cases you can see the tach move even if slight when cranks ensor is ok. the problem is , by the flowcharts for no spark, you would either have bad crank sensor or bad igntion module. I ahte to be in posotion to do a flip of the coin. Without scanner hooked up to see if you are getting a crank signal, this is exactly what i have to do, kind od guess. I just cant think what crossing the battery would have done to the ignition module nor cranks sensor BUT,, most all circuits are fuse protected so they would have blown first. My guess? crank sensor. can it be module? yes. You have few choices. swap out crank senosr, swap out ignition module or have a shop check the cranking signal from the crank sensor. 800 ohms may? mean its bad. It is out of range. Iw ish I had more. I really do not think ECm at this point. you would have lost other things like injectors pulse etc.


Lower Right Side of Engine


Randall C, ASE Certified Technician
Category: Car
Satisfied Customers: 11434
Experience: 32 years Foreign / Domestic Cars All aspects of Diag and Repair
Randall C and 16 other Car Specialists are ready to help you
Customer: replied 3 years ago.
Sounds good. I'm at least glad that it isn't 100% the computer. I'll start with swapping the sensor and see what that does. I get really lost when it comes to electrical problems so thanks for all your help.
Customer: replied 3 years ago.
Update: I changed the crank sensor first but that didn't change anything so I swapped out the ignition module and it fired right up. Thanks again for all your help.
Expert:  Randall C replied 3 years ago.
I am sorry the crank sensor was not the problem at first thus saving the expense, but it was down to one or the other. A scanner would have confirmed the sensor good or bad. But i guess on the brighter side, you got it running and cheaper then a computer . LMK if I can help again. Thanks

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Randall C
Randall C
Auto Technician / Consultant
1444 Satisfied Customers
32 years Foreign / Domestic Cars All aspects of Diag and Repair