Chevy Senoma 2000 computer problem

eliang · 07-01-2009, 02:31 PM

Hi Guys......
In a bit of a spot here......Proud of my chevy truck, got it christmas
08.... auto 2.2ltr, 4cyl works great but a week ago i think the fan clutch went bad it overheated and burn't the head gasket and warp the head and
destroyed the radiator....got all that redone last week....got the truck back over the weekend....went to work monday got home late in the evening but all went well.....tuesday got ready to go to work,went to warm up but it would not start for nothing......started to trouble shoot, remove filter from
inside chasy, fuel is clean and pump has good pressure.... remove battery
pole left of for about 45min, put back on but no starting .....so remove again
and left of for 2hrs in that time checked all relays and fuses all connectors blow out air cleaner .....went for lunch came back put cable on battery cranch and it starts but it use to give check engine message now it does not ...since i am missing a level senser from below the brakes reservoir it gives a check engine light all the time thats gone only security light comes on all the time and it does not want to start .......i think the mechanic tried
to change some setting in the computer to make the truck idle at 800 rpm because before it idles at 1100rpm until the ac is turned on then it goes to
945 after it has warmed up.....can he have done damage to my computer that way or corruped the setting in the memory somehow .........
Any help would be apreciated..........
Thanks in advanced
eliang

**octaneman** · 07-01-2009, 04:49 PM

Hi eliang

If the mechanic tried to remove the trouble codes manually and crossed the wrong pins on the ALDL connector, the result would be that the check engine bulb got burned. As for the computer getting damaged, there is that possibility, but trying to prove that there was malicious or careless intent on the mechanic's ability to solve the no start problem and damaged the ECM, will be extremely difficult. My advice to you is to go find another mechanic who's got a good reputation and affordible rates who knows what they are doing and are equiped to do EFI troubleshooting.

eliang · 07-03-2009, 07:43 AM

Hi Octaneman........
I am alittle mechanical minded......so i opened up my computer for the truck and checked every diode and ic i found one big ic thats read shorted while the other right beside it read different...ive learnt that u can check an
ic by putting the meter lead on pin 1&2 of the ic ie (positive on 1and negative on 2 and visa versa) and check the reading .......there are 2 same ic on one side ......so i put some cpu compound on all the ic and screwed it back together, then i got another a mechanic with an efi tester to check it
again but he still haven't gotten any codes and the security light still comes on but now the truck starts.......i cannot understand .........and i don't thing he shorted any pins on the cpu.....he has one of the older red and black efi tester that u have to add the module for the different model vehicle .....also id like to know if a cam or crank sensor do this?..........

thanks in advance
eliang

**bruiser** · 07-03-2009, 11:17 AM

Disconnecting the battery will erase the codes. If there is a problem, it will come back again.

Does the security light go off after the truck starts?

**octaneman** · 07-03-2009, 07:41 PM

General Motors ECM processors usually consists of a EPROM ( Electrical Programmable Read Only Memory) or a Flash Prom and a driver. To successfully test the EPROM it must be set on a electronic bread board connected to a circuit. Depending on the circuit configuration, taking the voltage readings on the VCC side of any IC may give a false positive because the circuit will require other inputs in order to affect it. The EPROM can be erased in one of 2 ways, either electronically or by using a U.V light. ECM voltages do not go above 14V anything higher will burn the ECM, so I'm not sure how you tested it, if there is a way to test the ECM just by probing the pins you mentioned then I'm not aware of it. The cam and crank sensors only do one function: 1) The crank sensor tells the ECM that the piston is at TDC and 2) the cam sensor tells the ECM when to give the spark at the coil(s). If either of them are open, or shorted the computer will set a no start condition and the engine will not start at all. After you re-seated the IC's with the compound, the ECM codes were completely erased when power was interupted, and i'm curious to know if the check engine light now comes on at ignition start. If you can get the numbers off the IC's and posting them, the manufacturer of those ICs can be identified.

eliang · 07-11-2009, 04:14 PM

Hi Octaneman..........
sorry i was away...........the security light stays on after the truck starts...and i am in the same no start situation again, i was just pulled in off
the highway once again......to answer ur question about the ic i would have to take apart the cpu again ......i guest i will have to try a next cam and crank sensor ......just got the ecm computer guy to run a check only 3 codes
1 for oxygen sensor 1 for transmision and 1 for sensor in the fuel tank i know was bad......ive got a friend who has an S10 99 with the same engine as my gmc sonoma 2000 2.2 ltr 4 cyl.....i'll see if i can try his sensors......
thanks in advance

eliang

**octaneman** · 07-11-2009, 08:28 PM

Welcome back eliang.

The security light on the truck should be disabled once it starts, but it does not,this leeds me to believe that your no start condition is attributed to GM's pass lock system.There should be a kit available to bypass the security feature on the truck, since you got the truck started, the cam and crank sensors are functioning so you can rule those out. The oxygen sensor though is another matter, the computer detects O2 sensor code affecting the air/fuel mixture. The O2 sensor has to be tested with a DVOM and then inspected for any deposits on it.

Do other electrical systems on the truck like locks, radio, lights, go haywire ?

eliang · 07-29-2009, 08:35 AM

Hi Octaneman.......
The problem has been solved......using donax auto trans oil the trans was slipping and that cause the security light to come on, hence making the truck not wanting to start.......when i purchased the truck i had changed
both oils but donax tg was the recomended so i went with that, but its a very thin oil, so it does not hold up the the work load and slips .......and i just found out by trial and error ......i went and replace the oil with lucas and change the filter too and boy was estatic by the move ......after it warmed up real good i had tires i could skide........so now i uses lucas for engine and trans ...........Thanks my bro for all the help and encouragement......oh i forgot to tell u about the oil......went to this autoparts store and when i enter it, i smelt this cherrypie smell so i ask the guy what it was if he got a new airfreshner and he said no it was a new trans oil by lucas boy it smell so good thats how i found it.....a little more pricey and the liquid is thick along with stabilizer..........

eliang

**octaneman** · 07-29-2009, 08:44 AM

Your welcome.

Thanks for letting us know the problem is solved.

07-01-2009, 02:31 PM	#1 (permalink)
eliang Registered User Join Date: Apr 2009 Posts: 21 OS: XP pro sp3	Chevy Senoma 2000 computer problem Hi Guys...... In a bit of a spot here......Proud of my chevy truck, got it christmas 08.... auto 2.2ltr, 4cyl works great but a week ago i think the fan clutch went bad it overheated and burn't the head gasket and warp the head and destroyed the radiator....got all that redone last week....got the truck back over the weekend....went to work monday got home late in the evening but all went well.....tuesday got ready to go to work,went to warm up but it would not start for nothing......started to trouble shoot, remove filter from inside chasy, fuel is clean and pump has good pressure.... remove battery pole left of for about 45min, put back on but no starting .....so remove again and left of for 2hrs in that time checked all relays and fuses all connectors blow out air cleaner .....went for lunch came back put cable on battery cranch and it starts but it use to give check engine message now it does not ...since i am missing a level senser from below the brakes reservoir it gives a check engine light all the time thats gone only security light comes on all the time and it does not want to start .......i think the mechanic tried to change some setting in the computer to make the truck idle at 800 rpm because before it idles at 1100rpm until the ac is turned on then it goes to 945 after it has warmed up.....can he have done damage to my computer that way or corruped the setting in the memory somehow ......... Any help would be apreciated.......... Thanks in advanced eliang

07-01-2009, 04:49 PM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 549 OS: WINXP	Re: Chevy Senoma 2000 computer problem Hi eliang If the mechanic tried to remove the trouble codes manually and crossed the wrong pins on the ALDL connector, the result would be that the check engine bulb got burned. As for the computer getting damaged, there is that possibility, but trying to prove that there was malicious or careless intent on the mechanic's ability to solve the no start problem and damaged the ECM, will be extremely difficult. My advice to you is to go find another mechanic who's got a good reputation and affordible rates who knows what they are doing and are equiped to do EFI troubleshooting.

07-03-2009, 07:43 AM	#3 (permalink)
eliang Registered User Join Date: Apr 2009 Posts: 21 OS: XP pro sp3	Re: Chevy Senoma 2000 computer problem Hi Octaneman........ I am alittle mechanical minded......so i opened up my computer for the truck and checked every diode and ic i found one big ic thats read shorted while the other right beside it read different...ive learnt that u can check an ic by putting the meter lead on pin 1&2 of the ic ie (positive on 1and negative on 2 and visa versa) and check the reading .......there are 2 same ic on one side ......so i put some cpu compound on all the ic and screwed it back together, then i got another a mechanic with an efi tester to check it again but he still haven't gotten any codes and the security light still comes on but now the truck starts.......i cannot understand .........and i don't thing he shorted any pins on the cpu.....he has one of the older red and black efi tester that u have to add the module for the different model vehicle .....also id like to know if a cam or crank sensor do this?.......... thanks in advance eliang Last edited by eliang; 07-03-2009 at 07:48 AM.

07-03-2009, 11:17 AM	#4 (permalink)
bruiser TSF Enthusiast Join Date: Jul 2005 Posts: 1,974 OS: xp	Re: Chevy Senoma 2000 computer problem Disconnecting the battery will erase the codes. If there is a problem, it will come back again. Does the security light go off after the truck starts?

07-03-2009, 07:41 PM	#5 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 549 OS: WINXP	Re: Chevy Senoma 2000 computer problem General Motors ECM processors usually consists of a EPROM ( Electrical Programmable Read Only Memory) or a Flash Prom and a driver. To successfully test the EPROM it must be set on a electronic bread board connected to a circuit. Depending on the circuit configuration, taking the voltage readings on the VCC side of any IC may give a false positive because the circuit will require other inputs in order to affect it. The EPROM can be erased in one of 2 ways, either electronically or by using a U.V light. ECM voltages do not go above 14V anything higher will burn the ECM, so I'm not sure how you tested it, if there is a way to test the ECM just by probing the pins you mentioned then I'm not aware of it. The cam and crank sensors only do one function: 1) The crank sensor tells the ECM that the piston is at TDC and 2) the cam sensor tells the ECM when to give the spark at the coil(s). If either of them are open, or shorted the computer will set a no start condition and the engine will not start at all. After you re-seated the IC's with the compound, the ECM codes were completely erased when power was interupted, and i'm curious to know if the check engine light now comes on at ignition start. If you can get the numbers off the IC's and posting them, the manufacturer of those ICs can be identified. Last edited by octaneman; 07-03-2009 at 07:49 PM.

07-11-2009, 04:14 PM	#6 (permalink)
eliang Registered User Join Date: Apr 2009 Posts: 21 OS: XP pro sp3	Re: Chevy Senoma 2000 computer problem Hi Octaneman.......... sorry i was away...........the security light stays on after the truck starts...and i am in the same no start situation again, i was just pulled in off the highway once again......to answer ur question about the ic i would have to take apart the cpu again ......i guest i will have to try a next cam and crank sensor ......just got the ecm computer guy to run a check only 3 codes 1 for oxygen sensor 1 for transmision and 1 for sensor in the fuel tank i know was bad......ive got a friend who has an S10 99 with the same engine as my gmc sonoma 2000 2.2 ltr 4 cyl.....i'll see if i can try his sensors...... thanks in advance eliang

07-11-2009, 08:28 PM	#7 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 549 OS: WINXP	Re: Chevy Senoma 2000 computer problem Welcome back eliang. The security light on the truck should be disabled once it starts, but it does not,this leeds me to believe that your no start condition is attributed to GM's pass lock system.There should be a kit available to bypass the security feature on the truck, since you got the truck started, the cam and crank sensors are functioning so you can rule those out. The oxygen sensor though is another matter, the computer detects O2 sensor code affecting the air/fuel mixture. The O2 sensor has to be tested with a DVOM and then inspected for any deposits on it. Do other electrical systems on the truck like locks, radio, lights, go haywire ? Last edited by octaneman; 07-11-2009 at 08:39 PM.

07-29-2009, 08:35 AM	#8 (permalink)
eliang Registered User Join Date: Apr 2009 Posts: 21 OS: XP pro sp3	Re: Chevy Senoma 2000 computer problem- Solved Hi Octaneman....... The problem has been solved......using donax auto trans oil the trans was slipping and that cause the security light to come on, hence making the truck not wanting to start.......when i purchased the truck i had changed both oils but donax tg was the recomended so i went with that, but its a very thin oil, so it does not hold up the the work load and slips .......and i just found out by trial and error ......i went and replace the oil with lucas and change the filter too and boy was estatic by the move ......after it warmed up real good i had tires i could skide........so now i uses lucas for engine and trans ...........Thanks my bro for all the help and encouragement......oh i forgot to tell u about the oil......went to this autoparts store and when i enter it, i smelt this cherrypie smell so i ask the guy what it was if he got a new airfreshner and he said no it was a new trans oil by lucas boy it smell so good thats how i found it.....a little more pricey and the liquid is thick along with stabilizer.......... eliang Last edited by eliang; 07-29-2009 at 08:44 AM.

07-29-2009, 08:44 AM	#9 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 549 OS: WINXP	Re: Chevy Senoma 2000 computer problem Your welcome. Thanks for letting us know the problem is solved.