Ecu?

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Guest

Ecu?

Postby Guest » Mon Jan 20, 2003 10:57 am

I have a 91 Cavy that I transplanted the 2.8 and 5 spd from a 90 Beretta into. Along with front suspension, brakes etc...Everything bolted in nicely, Used complete engine harness and computer from the beretta. Problem!!!!! There is no signal to the fuel pump (works when straight wired) and no power at the coils.  All my dash lights work and the engine will turn over.  but I cant get any computer codes. HELL I cant even get a signal on the test circuit with a volt/ohm. Is it possible the computer isnt getting any power???  I have 3 ECUs to work with.  Where is the easiest dplace to access the main power line for the ECU and is it a set or variable voltage in????   Thanks for ANYTHING!!!!



Guest

Ecu?

Postby Guest » Mon Jan 20, 2003 11:35 am

the starter and interior lights have no interface with the ecu. fuel pump and ignition do though. it def sounds like you have no power at the ecu if you cant get the daig terminal to give you anything.  

a quick check would be to disconnect the air intake temp sensor, located on the air box, or intake tube, and with the key in the run position, check the harness of the AIT for 5vdc. if you do not have this, the ecu is not powered up.

the ecu should have power on several lines. i cannot tell what the ecu connector numbers are, so i will give you some other wires to check that are connected to those pins.
power= check the pink/black wires on the fuel injectors (with key in run)
          for 12 vdc. if not, check fuse #1 in the fuse box. 15 amp.
          check the orange wire on the fuel pump relay for 12vdc. if not,
          check the inline fuse on that wire (somewhere, donno) 20 amp
ground= again, i cannot tell the pin numbers, but you should have three
           black/white wires out of the ecu which should all be connected
           to ground.
depending on what you find here, you may want to double check everything on that wire harness for proper connections to the right signals.
good luck:)



Guest

Ecu?

Postby Guest » Mon Jan 20, 2003 11:36 am

also, check www.jbody.org



Guest

Ecu?

Postby Guest » Mon Jan 20, 2003 9:41 pm

Thanks the tests shall be done in the morn....  If the Ecu doesn't have power and I can't find the problem.  What do you think of straight wiring the ecu off a switch, or making a relay off the ign. switch.  Like I said I have a couple to play with! :D :D



Guest

Ecu?

Postby Guest » Mon Jan 20, 2003 11:19 pm

did you only replace the engine wire harness?  what im afraid has happened is when you replaced the engine bay harness, its pin out is different than that of the rest of the car(where they connect). for instance, your key "RUN" signal is not getting to the ecu, the connector at the fire wall may have signals on different pins on one side than on the other. if that is true, how many other signals might have been crossed?  it could take a very long time to sort through them.

for starters, yes you may wire the ecu directly up to the battery through a switch without any reprocusions. this will turn the ecu on, but if the signal cant get through that firewall connector to turn on the fuel pump, then you will still have no start. you may also hardwire the fuel pump in and force it on.  that should be the only thing the ecu has to interface with to be happy and let the ignition go to work.

if you are going to hardwire the ecu (strongly recommend for testing purposes only), i would suggest tapping into the same wire on the fuel injectors i spoke of earlier.  you will also need to check at the ecu for ground on the three black/white wires. that should be all it takes to get the car started. ÂÂÂ

be prepared though, and have a fire extinguisher handy!  when you basstard rig a circuit, unexpected things can happen, and you dont wanna get caught by suprise.

i hope you just do this to verify that the engine does fire up, and dont plan on driving it around in this state.  you will be defeating ALOT of saftey precautions GM has implemented.  :)







Guest

Ecu?

Postby Guest » Tue Jan 21, 2003 9:15 am

I replaced entire harness from ecu to engine.  I broke all the sealing goop from around the firewall connector and took it along with everything else.  There shouldnt be any breaks or differences than when it was in the beretta.  And yes I have 2 fire extinguishers ready...  10 years working on cars does teach you SOME :D :rock:  Lessons.  I just normally deal with Nissan.



Guest

Ecu?

Postby Guest » Tue Jan 21, 2003 3:48 pm

IT LIVVVVVVVVVVES!!!!!!!!!!!!!   Okay I ran the extra tests and nothing... :(  So i ran a 12gauge line from the fuse box IGN. connector with a 10 amp fuse inline.  Hooked this to a pink/black line at firewall junction and VOILA!!!  Runs better than it did when it was in the beretta..  BY the way the Beretta body and interior were trashed, so I didnt kill a good car for this project and I only had 150 in the Cavy :0



Guest

Ecu?

Postby Guest » Tue Jan 21, 2003 9:15 pm

sweet man, glad to hear it! good luck with the rest of your project.



Guest

Ecu?

Postby Guest » Wed Jan 22, 2003 2:46 am

THANK YOU FOR THE HELP MAN!!! :cool:



Guest

Ecu?

Postby Guest » Wed Jan 22, 2003 7:34 pm

I know on my car, there is a fuse on the firewall near the relays that, if blown, will present these same results. ÂÂÂ Probably too late for this info, but something you could check if you just simply want to know what was wrong.  It is in a black casing that you have to un-clip to take apart, and there is a standard box shaped fuse inside of it which runs the main power to the ECM.







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