ecm high voltage 89 camaro 2.8 mpfi - Team Camaro Tech
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post #1 of 9 (permalink) Old Nov 18th, 06, 06:44 AM Thread Starter
 
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ecm high voltage 89 camaro 2.8 mpfi

check engine came on, code 34 replaced maf sensor, code came back, checked voltage at maf sensor plug middle wire, read 10.3 volts, should be at 5 volts ?, checked wire for short to voltage (test lite from middle plug in to ground, no lite) = bad ecm replaced ecm check eng lite off now but middle plug in on maf plug in still reads 10.3 volts help?
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post #2 of 9 (permalink) Old Nov 18th, 06, 12:45 PM
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Re: ecm high voltage 89 camaro 2.8 mpfi

You might want to unplug the MAF connector and check continuity from the ECM connector to the MAF connector and to ground. Five volts goes out to semsor, any one of them, goes through the circuit, whatever it might be, and the return to ECM to tell ECM the condition is being sensed. There should be a minimal amount of voltage to chassis ground, and this difference should be seen on 5 volt reference voltage also. The ECM provides its own ground for the sensors. None get referenced to ground.

Also, check 5.0 volt at other sensor connectors to see if 5 volt regulator is broke or has a bad ground. Check all grounds in engine harness and ECm ground(s).

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post #3 of 9 (permalink) Old Nov 18th, 06, 01:51 PM Thread Starter
 
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Re: ecm high voltage 89 camaro 2.8 mpfi

Thanks for the info. Gonna go check things out and will get back to you in the next day or two. thanks again..
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post #4 of 9 (permalink) Old Nov 18th, 06, 02:22 PM
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Re: ecm high voltage 89 camaro 2.8 mpfi

Good luck. I'm sure you've tried over at www.thirdgen.org

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post #5 of 9 (permalink) Old Nov 20th, 06, 07:39 AM
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Re: ecm high voltage 89 camaro 2.8 mpfi

I have seen the connector pins loose their tension and not make good contact on than generation of MAF sensors. But the 10.3 volts has me stumped. The voltage should be 5 volts that the ECM supplies to the plug and the MAF will pull the voltage down to ground. At least this is true for voltage control MAFs. I'm not sure what the requency control MAFs have for a voltage signal, but I'd presume 5V as well.

Have you tried measuring that voltage with the MAF disconnected? I'm just wondering if the MAF is supplying the 10.3 volts or if it is in fact coming from the ECM / wiring.

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post #6 of 9 (permalink) Old Nov 23rd, 06, 04:30 AM Thread Starter
 
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Re: ecm high voltage 89 camaro 2.8 mpfi

wellll, sorry for the question, my stupidity reigns here.started checkingbattery & alt put volt meter on battery read 25 volts had volt meter set on wrong setting sooo apologies do appreciate all help thanks
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post #7 of 9 (permalink) Old Nov 23rd, 06, 04:51 AM
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Re: ecm high voltage 89 camaro 2.8 mpfi

But you learned something. You're welcome.

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post #8 of 9 (permalink) Old Nov 24th, 06, 08:33 AM
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Re: ecm high voltage 89 camaro 2.8 mpfi

No worries Jeff. So do you see 5V at those points instead now? I presume you've got a code set still. Let's just move on and pretend like the meter thing didn't happen.

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post #9 of 9 (permalink) Old Nov 25th, 06, 04:10 PM
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Re: ecm high voltage 89 camaro 2.8 mpfi

Quote:
Originally Posted by jeff mushrush View Post
check engine came on, code 34 replaced maf sensor, code came back, checked voltage at maf sensor plug middle wire, read 10.3 volts, should be at 5 volts ?, checked wire for short to voltage (test lite from middle plug in to ground, no lite) = bad ecm replaced ecm check eng lite off now but middle plug in on maf plug in still reads 10.3 volts help?
It is not uncommon for the 5 volt referance line to share common sensors.Look for other 12 volt sources that can leak into the 5 volt ckt inside connectors.Under car is usually the first place to start.For example,running only a fuel pump 12 volt supply can run to a 5 volt referance if moisture has contaminated the common connector.An ac pressure sensor can also contribute to this.I would look at a schematic and try to link the ckts.Good luck.George
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