ECM problem

Hi there,

Thank you for the donation,

If the ECU is suspected of being faulty you may have the option of testing the car with a test ECU, ask your EFI specialist if any company offers test units to run in the car, here in Aust we can get a good known ECU to test the car to determine if the problem is in the ECU, if not there is only a small charge for the use of the ECU, this may be an option open to you, this will save many $$$ if the problem is not an ECU fault and you go purchase one, check this out.

mark (mhpautos)

well i found an ecm on ebay for $79 usd. It is the same part number from the one i removed but it is the newer remanufactured one with -84 part # on the end. the very same one as on the website link I provided above. It was out of a salvaged car. I am waiting to receive it and install it. do you know if the odometer reading will change? I am thinking that if i replace the ecm with this newer remanufactured one it will fix the problem. The van was running when I had the obdII cable plugged in and someone mentioned the ecm may not be grounding out things correctly.

The speedo reading will not change, the used ECU may well solve the problem, but you have to be prepared to keep it if it does not as i am sure that they will not take it back, that is why i use the test and return system here, but as it is quite cheap, this may well be an option open to you, and if it does not work you can always sell it on again, this is now getting to the point that it need to be inspected first hand as working blind like this has some draw backs, i am going to have a read up on your system this week ens and i will post any further thoughts soon.

mark, (mhpautos)

well, i have not put the ecm in yet. it is a newer remanufactured model of the correct part number for my sienna though, so i am guessing it is not made in 2001, it has since been changed at one time. i dunno. I hope you could figure out why my car would run with the OBDII cable hooked up and die when it is pulled. Where is the connection #8 i believe where someone said I should look? a schematic so i could identify pins on the ecu will help me.

well i got the other ECM from ebay that I bought and I hooked it up and it did not work at all. This time with the 2nd ECM installed it now will not start. Before with original ECM, the van would start only with the OBDII cable connector plugged in. Now with the 2nd ECm, the van will not start. So, this leads me to believe that it is an ecm problem and I should take the original ECM and have it sent to be refurbished but am I still working in the blind? Is a ECM refurbisher legitimate?

Yes it is, that is what i spoke of in earlier posts, getting a known good test unit, some manufactures offer this service, i just don't know who in you part of the world does it,larger parts suppliers that deal with the trade may have information on this.

Mark.

what do you mean by a known good test unit? use a re furbished one?

Yes, I would expect that the larger fuel injection specialist company's, (ask your mechanic about this) may do trial units, if it fixes your problem you purchase it, if not you pay a small fee to get the test unit re certified serviceable and you look further for this error. you will have to ask your mechanic if this practice is done in the USA, we do it in Aust.

Mark

Well my van is at the dealer and i drove it there with the obdII connection cable connected. I provided them with the original ECM unit(the one installed in the van). I also provided them with another ECM unit with the -84 part number and its the remanufactured unit. They can see that the van will start and run with the OBDII cable connected to the van. Also, what is involved with programming an ECM to a vehicle once you have a replacement one? I called an ECM refurbishing shop and they said even though I have a replacement ECM, it will still have to be reflashed to the vehicle. What can anyone tell me about how they do that?

well, the dealer said it is a ground problem in the ecm and the 2001 ECM is a plug and play unit and does not require reflashing. I have to buy an ecm and put it in. I am having trouble finding an ecm

Have you contacted your local auto parts supplier, i do not see why this should be hard to find.

mark

well i bought one from a salvaged van that was running. Same exact everything, part numbers, etc etc. Installed it, the van started up for about a second then died out. I hooked the OBDII tester cable back on and the van ran again with the OBDII tester cable plugged in. How do I check to see what circuits are being completed with the OBDII test cable plugged in? I am thinking maybe something is causing the computer to fail shorting it out or something. Could a faulty circuit burn up the computer? How can I trouble shoot the OBD II diagnostic connection port? I want to know which pins and circuits are causing the OBDII connection port to complete the circuit for the computer.

I hope that this is clear enough, i had to sent is as two and blow it it up as the original was far to small to read easel. mark (mhpautos)

Thank you for the wiring diagram! I copied it and tried to blow it up but was not readable. can you send it a different way or put it in a webshot or photobucket link so I can view it? There are only five wires on the back of the OBDII test connection port. Black, red, Pink with black tracer, brown and i believe white........A readable diagram will help.

i will see what i can do,

mark

i sent you my email address so you could send the diagrams to me.

I still need a nice wiring diagram that I can see in order to troubleshoot what circuit might be faulty and causing my ECM. I sent a PM to you with my email address so you can send me a wiring diagram.

Mitchell 1 (where this diagram comes from) will not allow me to copy this pic, and so far any capture i try still give me the fuzzy pic, i will ask a comp tech what to do, as this is a bit out of my computer skills , i have never had this problem before so please bear with me on this please, i am working on it.

mark.

The original is way to small and it looses quality even blowing it up a little. Is this any better for you? mark.

well i cannot view it at all when i try to blow it up a little. i just save it to my desktop and open it and blow it up then it gets blurry even opening a little slightly

i got the diagrams from the link you sent now I have some questions. On the data link connecector behind the dash to the right of the steering column on the wiring diagram four of the connector pins are labled: (TC) pink/black, (SIL) red, (CG) white/black, (Bat) black. What do these labels mean? (SIL) is the red wire on the diagram and it shoes it going to the ECM. The pink/black wire (TC) also goes to the ECM. Now the question is why does my van run when I connect thr OBD tester to the van? Initially also the new computer I stuck in there worked for 1/2-1 second then stopped.

I am going to see a specialist in ECU problems, i am starting to run out of ideas, with out having it in front of me, this is becoming very frustrating, i hope to be able to post something soon, trouble is, these people will want the car to test, but i may get something of help with a call.

mark

ok please please please help.

The tech said that with this type of problem, it should be looked at by a tech with a very good understanding of engine management problems, it is important to eliminate all probable causes one by one, he also said that in all his years he had never come across such as problem, one suggestion was to do a continuity test through each ECU wire to test for a high resistance or a earth leak, if a new ECU has been fitted we can eliminate this a problem, so logic says that the issue is loom related or a sensor or driver that is back feed a current that is shutting down the ECU, now this is a time consuming thing to take on, he suggests that testing the fault gathering capability of the ECU first is where to start, that is disconnect a sensor and try and start, then do a scan to determine that the ecu is reading faults correctly, also he said that if you can get a scanner with live data read out a tech can check many systems are incorrect value without actually doing a hands on bench test of each item, a fer things to get on with.

Mark (mhpautos)

maybe the computers I have are good and it is just a sensor or loom that is hindering the computer for starting. A good ECU, but a sensor or wire with wrong values not allowing the ECU to function properly? I should check ech wire going to the ECU for short to ground?

With out having this in front of me to check first hand is really difficult, especially a problem that is not able to be resolved by conventional wisdom, as for why the engine will run with the OBD11 tester connected only, that I just don't know, i have no idea as to the workings of the tester that will over ride what every is causing this problem, maybe if you contact the manufacturer of the tester and ask there tech department they may have a better idea as to why it is so, this post is now on our moderators board for all the techs to see, i can only hope that one of them can shed some new light onto this, often fresh eyes can see what we are now blind to.....

mark (mhpautos)

I have gone back over all the posts, and this stands out....


I pulled the scan tool itself and left the cord on and the van continued to run with just the cord plugged in. Cord gets warm a little. Once I pull the cord it dies out.

what type off scanner are you using? with the cord still attached is it still able to run) which wires to which pins feel warm? what is the connection like to look at? is it just a loon with a plug to fit both ends? is there a interface that you also have plugged in? there must be some sort of circuit associated with this "cord" as if it is, it will just be individual wires between to plugs and this will do nothing,

sorry about all the weird questions but i am really grasping at straws just now to come up with some form of attack to sort this out.

Mark (mhpautos)

i am using an INNOVA 3100 tester. I will take pictures of the connections. the cord, the tester etc. Thanks I understand cars, so don't worry about so many questions. I am an airplane mechanic and a car mechanic. i also went to universal tech institute in 1991

With your back ground, then i am sure that you can understand my own frustration with this, have you considered the last set of questions i sent?

mark

I think that there is a circuit associated with the cord because if there was no circuit the cord would not do anything

A continuity test of the adaptor loom would show up, if you get 0 ohms resistance down each wire, that should tell you, would you agree?

Mark (mhpautos)

which loom are you referring to? I should read out the van's data link connection or the black OBDII tester cable? The black tester cable to see how the circuit of the cable is set up? We know it is the cable that is sending power through/or grounding a circuit to make the van run.

The OBD scanner cable, i cant see how that is creating a circuit.

the main problem is that with the cable plugged in it is making the van run so it is allowing a pin to cross over to another pin. So I should run the continuity test on the OBD tester cord to see what it is doing when it is plugged in.

Yes, so i would be checking that cable independently first,

also just to let you know, in a few days i will be away for about 1 week, so i may not be able to reply as i wont have any access to a network where i am going.

mark

I jumpered the data link connection on the van. it is the 2 together in the middle on the bottom row. I jumped it with some wire and it got very very hot. the van started and ran. this should help us now. What do you guys think now?

This is the schematic of the data link connector, what is the colour of the 2 wires you have bridged out?

mark

white/black & brown