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Dan
Dan, Technician
Category: Car
Satisfied Customers: 21477
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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i have a 1993 isuzu rodeo with a 3.2 engine and 5 speed tranny.

Customer Question

i have a 1993 isuzu rodeo with a 3.2 engine and 5 speed tranny. she was driving it after having to put a clutch, rotors,and ball joints in it. ran good for say 5 days then just shut off. fuel pump not kicking in. checked fuel pump its good. new relay , got a used ecm same problem. also its not sending a signal to injectors to fire.
Submitted: 11 months ago.
Category: Car
Expert:  C. Walker, Jr. replied 11 months ago.
Does the check engine lamp turn on with the key on?
Customer: replied 11 months ago.


no it dosent.

Expert:  C. Walker, Jr. replied 11 months ago.
You have a wiring problem most likely.

http://snk.to/f-cdhfda03

Check computer powers and grounds. Check for computer 5 volt reference possibly shorted to ground. Has B+ on terminal A6 at the computer. Has 1.8 volts or so on B1 and C16. Looking for splice S146. I searched and can not find it listed anywhere. Try jumping power to either of those terminals-won't hurt anything-and see if the other terminal gets hot. See if the CEL comes on then key on, and if it runs then too. Can ground the CEL at the computer and turn it on.Need good B+ to the computer first. Computer grounds must be checked.
Customer: replied 11 months ago.


a guy checked sat for me ecm is getting power, not sure what you mean b+ termial A6 and so on


 

Expert:  C. Walker, Jr. replied 11 months ago.
12v is B+ The pin out is above click the link to download. I need you to check these for me. You either have a faulty ecm or wiring concern here.
Customer: replied 11 months ago.


ok i will. does the ignition control module have anything to do with power not getting to fuel pump relay and injectors and check engine light that not completing circut

Expert:  C. Walker, Jr. replied 11 months ago.
No it does not.
Customer: replied 11 months ago.


ok then it has to be in the wiring like u said . i even got a used ecm for it that i am being told is a good one and it has the exact same numbers as mine does. just dont understand why it ran good and just all of a sudden just shut off on her like that, have dash out and everything tracing wires for a bad wire and cant find any bad ones so far. i clicked on that link and its taking me a place called file snack whats this?

Expert:  C. Walker, Jr. replied 11 months ago.
You have to click the downloan button.
Customer: replied 11 months ago.


i did click the download button but then what dosent seem to do anything. tried to put it into public downlaods and im getting nothng

Expert:  C. Walker, Jr. replied 11 months ago.
It is like downloading any other file from the web. It is a PDF file you can choose to just open it. If it goes to public than you need to find the public folder on your computer.
Customer: replied 11 months ago.


ive tried that isnt working. what is it im suppose to be seeing

Expert:  C. Walker, Jr. replied 11 months ago.
This is the pin outs of the PCM. It shows each pin and wire color so you can do the testing. It is too large to add to the page but I can try.
graphic
Customer: replied 11 months ago.


can u send the pages to my XXXXX@XXXXXX.XXX account. u think maybe the ground for ecm isnt working then i take it

Expert:  C. Walker, Jr. replied 11 months ago.
It can be a ground or a shorted voltage wire. I cannot email. The page I sent will work just have to download a pdf viewer if you dont already have adobe.
Customer: replied 11 months ago.


ive been trying to download it with that link u sent dont understand how to do it all


 

Expert:  Dan replied 11 months ago.
Hello, my name is XXXXX XXXXX I'm here to help get your problem solved. Click on following link https://db.tt/IHaZWa9b for wire diagram to check power/grounds at the ECM. Assuming the ECM is good I agree with previous expert that you have a power/ground problem. Let me know if you have questions or run into questions, you can reply to this answer at any time without additional fees. Thanks.
Customer: replied 11 months ago.


i just did not getting the whole page or pages. its cutting it off just under think D8 map signal input wire

Expert:  Dan replied 11 months ago.

Oops, give me a minute and I'll upload the rest. Thanks.

Customer: replied 11 months ago.


ok. yeah i agree with other guy to about checking them. ive tried bout everything else i can think of.

Expert:  Dan replied 11 months ago.

Here are full diagrams, let me know if you have more questions or run into questions. Thanks.

-

https://db.tt/SjfWjG6o

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https://db.tt/4wIYZP1G

Customer: replied 11 months ago.


got them look confusing right now but ill keep looking at them lol. i even checked like the book said to run a jumper wire from 1 and 3 on dat link connector and check engine light didnt even light up that way to flash the codes. so u both feel its in the wiring going to the ecm then .


 

Expert:  Dan replied 11 months ago.

Here is also a connector diagram to help with testing. Remember you can reply to this answer at any time without additional fees so make sure to let me know if you run into questions. Thanks

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https://db.tt/0L11shd8

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https://db.tt/cjQNKQ1L

-

 

Customer: replied 11 months ago.


thank you those two are a major help thankyou

Expert:  Dan replied 11 months ago.
No problem, I am happy I could help. Let me know how it turns out or if you run into questions. Thanks again and have a great day.
Customer: replied 11 months ago.


just one thing can you tell me again how im checking these wires and which ones and what im looking for

Expert:  Dan replied 11 months ago.

Lets keep this easy. Replace ECM relay and let me know if that helps, thanks.

-

Here is a picture of relay https://db.tt/63e4TMMD

Customer: replied 11 months ago.

have already tried that sat. getting power to ecm from relay

Expert:  Dan replied 11 months ago.

So your getting power on pin A6 of ECM while trying to start?

Customer: replied 11 months ago.


that im not sure yet. how do i check that? do i unplug that connector to ecm to check that pin or how then i will check that

Expert:  Dan replied 11 months ago.
You need to backprobe back side of connector with paperclip with it still plugged in to see if it is getting power. We can do some other testing though. Remove ECM relay and see if pin 5 has voltage with key on, pin 3 should have voltage at all times, and pin 4 should have ground at all times. Check that and let me know, thanks.
Dan, Technician
Category: Car
Satisfied Customers: 21477
Experience: Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
Dan and 15 other Car Specialists are ready to help you
Customer: replied 11 months ago.


have some questions for u if your on

Expert:  Dan replied 11 months ago.

What are the questions? Thanks.

Customer: replied 11 months ago.


i looked at the wires on the rodeo dont see any where the power can be shorting to gronund


 

Expert:  Dan replied 11 months ago.
Were you ever able to check all of the power/grounds going to the ECM?
Customer: replied 11 months ago.


thats the other question. shld i use a test light to check all the power wires going to the ecm? and a continuity check from ground wires to the battery ground?


 

Expert:  Dan replied 11 months ago.
A test light would work best.
Customer: replied 11 months ago.


for the powers to the ecm are they just the ones that are listed as battery feed like C 16, B1 and the grounds called system grounds, whats the best way to check the grounds to see if they are grounding right, like from back of ecm to where. cwalkerjr21 had said check computer 5 volt reference possibly shorted to ground. has B+ on terminal A6 at comp. has 1.8 volts or so on B1 and C16. said try jumping power to either of them terminals and see if other terminal gets hot. see if cel light comes on and if it runs. not sure exactly what he means can u explain that little better for me

Expert:  Dan replied 11 months ago.

B1 and C16 should have 12v, so that is a problem. These pins get voltage from fuse 1 which is a 15 amp fuse. Check to see if fuse has 12v, if fuse has good voltage but not pins b1 and c16 then check splice 146 which I do not have a picture of but if you follow red/white wire from fuse box it will lead to splice.. If splice 146 is good then you have a wiring problem somewhere on red/white wire that goes between fuse and ECM. Let me know if you run into questions, thanks.

-

Here is wire diagram https://db.tt/4wIYZP1G

Customer: replied 11 months ago.


fuse 1 is that located in the relay box under hood or under the dash? the ecm does it ground thru the system ground wires or the 3 bolts on the side to bracket that holds it? after i check power and grounds just wondering. when u turn the key on should i get power out of ecm on the pink and white wire going to fuel pump relay


 

Expert:  Dan replied 11 months ago.
Lets just deal with one problem at a time. If those two pins have low voltage that is a problem then we will move onto other things. Fuse 1 is located in fuse box under hood. Let me know how it goes, thanks.
Customer: replied 11 months ago.


forgot i to test for the voltage the key switch is in the run position am i right

Expert:  Dan replied 11 months ago.
No, key does not need to be on because it should have voltage at all times. Let me know how it goes, thanks.
Customer: replied 11 months ago.


sorry meant when i check for 12 volts at B 1 and C 16 terminals does key need to be on

Expert:  Dan replied 11 months ago.
No, they get voltage at all times which comes from the fuse. Let me know if you run into questions, thanks
Customer: replied 11 months ago.


thanks ill go check that


 

Expert:  Dan replied 11 months ago.

No problem, keep me updated. Thanks.

Customer: replied 11 months ago.


just checked that out. i have mulitimeter set on symbol V ----, with a solid line above the dashes set at 20. put black lead on ground and red on battery pos got 12.5 v. same on fuse and at both terminals B 1 and C 16

Expert:  Dan replied 11 months ago.
So we know those two wires have good power . Check C15, D1, C12, and A12 for ground. Let me know, thanks.
Customer: replied 11 months ago.


ok. just to make sure my brain is working right which is the best way to check they are getting a good ground. from the back of the ecm terminals to where.?

Expert:  Dan replied 11 months ago.
You can just unplug ECM and see if wires work to turn on test light when using as ground.
Customer: replied 11 months ago.


ok thanks. i know u may think im stupid by asking that but im not just want to make sure i do it right for u . only had 3 hours of sleep after getting home from driving 18 wheeler all night. used to be a deisel mechanic in the military but sometimes wiring still gives me a big headache lol

Expert:  Dan replied 11 months ago.
I'd rather have you ask questions to make sure it is done right then do it wrong. Let me know how it goes, thanks.
Customer: replied 11 months ago.


hooked test light clip to a ground wire on bolt on side of kick panel that has ground wires to it. checked all 4 of those wires on back of plugs and light didnt come on


 

Expert:  Dan replied 11 months ago.
Last wire we need to check on ECM. is to see if pin A6 has voltage with key in on position and while trying to start. Let me know, thanks.
Customer: replied 11 months ago.


ok figured if light didnt come on when checking ground we were good on that and not shorting to power some how right?


 

Expert:  Dan replied 11 months ago.
Lets check to see if pin A6 has power, I'm assuming it doesn't and if not we will have to test wires at ECM/main relay.
Customer: replied 11 months ago.

assuming it should be 12 volts both times too right. ill plug plugs back in ecm and try that


 

Expert:  Dan replied 11 months ago.
That is correct.
Customer: replied 11 months ago.


no i didnt get any reading for voltage at all. either way even tried with a paper clip to make sure i was getting the metal part lol

Expert:  Dan replied 11 months ago.
At engine relay 1 pin should have battery voltage, 1 should have ignition voltage, and one should have constant ground. Let me know which one is missing. Thanks.
Customer: replied 11 months ago.


ill check these from the bottom side of the relay box where the wires come into it right? battery voltage sholud be 12 as a constant, and ignition should be 12 with key on right? ground should be checked how?

Expert:  Dan replied 11 months ago.

You check ground same way you checked ground at ECM. Correct, check female pins relay inserts into for power\/ground. Correct about battery being constant and ignition being with key on.

Customer: replied 11 months ago.


test light didnt light up checking ground to battery ground. have 12 volts at battery constant, ignition wire has no voltage till u crank the engine, which i assume is way it should be, starts at .09 and drops to .07 and stays there

Expert:  Dan replied 11 months ago.

Ground is a problem then. This relay gets ground through ground 103, here is a picture. Clean ground let me know if that takes care of problem. Thanks.

-

https://db.tt/GAQToCFf

-

 

Customer: replied 11 months ago.


all of this also translates into the fuel pump not kicking in and check engine light not litghting up right?

Expert:  Dan replied 11 months ago.
Correct.
Customer: replied 11 months ago.


now i did check the ground wire the right way i hope. i hooked the test light to the ground on battery and touched the ground wire on the relay with the tip of test light . should it have lit up then


 

Expert:  Dan replied 11 months ago.
The test light need to get connected to positive on battery, then tip of light goes to where relay is.
Customer: replied 11 months ago.

started to think i did that wrong thats why i asked. just hooked it to battery pos and touched wire and lit up. sorry bout like i said my brains tired lol

Expert:  Dan replied 11 months ago.
Ok now we know you have good ground next step is to figure out why ignition power was missing. Check to see if 10 amp fuse in location 8 of interior fuse box has voltage with key in on position. Let me know, thanks.
Customer: replied 11 months ago.


sorry bout that. when u said check ground the same way as we did for ecm wires thats what i was thinking hook to ground to check if it lit up. going out to check fuse for power

Expert:  Dan replied 11 months ago.

Sounds good, let me know. Thanks.

Customer: replied 11 months ago.

says fuse 8 10 amp is for engine back L, has 12.30 volts on left and .01 on right side. says fuse 9 15 amp is ignition has 12.26 on both sides

Expert:  Dan replied 11 months ago.

If fuse only has voltage on one side that means fuse is blown, pull it out and check. Let me know, thanks.

Customer: replied 11 months ago.

i dont freakiin beleive this. i checked them fuses with one of them testers and it lit up on all fuses. i have the dash completly out so i could trace all wires to fuel pump and everything for a bad wire and now turns out just a fuse. even spent 100.00 on a used ecm figuring it could have been the problem


 

Customer: replied 11 months ago.


thanks a lot for all ur help !!!!!!!!!!!!!!!!!!. now to put the rodeo all back together lol. u are deffnitley getting an excelent rating and a tip. thanks again

Expert:  Dan replied 11 months ago.
Good to hear it is up and running. The fuse probably blew because of the ECM failing. If fuse blows again let me know and we figure out why. Thanks for update and have a good weekend.

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