Norwaybird

I have a problem with the ECM I think? I was trying to read out some codes by grounding the diagnostic terminal, but I don't get a code 12 when I turn the ignition on. The SES light just stays on with no flashing. Is my ECM bad or is it the memcal?
If I pull the TPS plug with the engine running (or any other connector - not in diagnostic mode), the SES light comes on so it seems to me that the ECM is detecting this. Because of the ECM setting the SES light I was hoping that the ECM was OK, but I'm not able to read out the trouble codes, so maybe a bad memcal can cause this?
I also think that I'm in "limp home" mode because my idle is kinda high and the car doesn't feel right.
It's a 87 T/A 305 TPI, and there was an Hypertech "chip" installed when I got the car.
Can someone please help me to find out if it is the ECM or the memcal that is bad??
How much is a new ECM?

brharris27370

Sounds like your not getting the ALDL plug jumped correctly. My plug jumps the upper right hand 2 connectors together to get diagnostics. Maybe someone installed the plug wrong or something. I would try all 4 corners and make sure you are getting into the metal prongs good.

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91 Camaro RS 5.0L Black Convertible 700R4
** Added so far **
*GM Wonderbar,Alston SFC's,spohn LCA's and Panhard rod
*Turbo City Inj Spacer
*Dual Snorkel Air Filter
*March Performance Pulleys
*GM 3.42 Gears with OEM Zexel POSI
*Edelbrock headers
*3" High Flow Cat
*3" Dynomax Exhaust
*Walbro 255 lph Fuel Pump
***Future 330hp Vortec Crate with LT4 hotcam and 454 TBI

Norwaybird

No, I don't think that's the problem. I was able to read the codes some while ago so the connector is OK.
Anyone?

Norwaybird

I still have problems with the ECM I think??
Well I have som other questions about trouble codes. If you pull the O2-sensor plug, will that set a code? If you pull the knock sesor, will that set a code?
Because I don't get any SES light if I pull the O2-sensor or the knock sensor. But if I pull the TPS, MAF or IAC plugg the SES light comes on.
Still no diagnostic mode, no code 12.
Bad ECM or bad EPROM??
Car runs OK, sligthly high idle sometimes, and it's knocking at WOT above 3500 rpm.

leirch

If you had a spare ECM or prom I would try them. You should set a code without a knock sensor or O2. I know I did when they were unhooked..

Brendan

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1987 IROC-Z L98,SR,EB 6085's,LPE 219/219 SR Cam, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, Aluminum DS, 94 Disk Rear, Adjustable Prop Valve, Precision 3.73 Gears, Weld in Sub-Frame Connectors, Hotchkis LCA's, KYB Shocks/Struts, Poly Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm, Big stereo, 730SD Conversion.

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Tonyrodz

Weird-my car's O2 isn't connected either and it doesn't set a trouble code. I run it all the time(codes)and always get a 12.

Norwaybird

Well now I'm a bit confused. Will disconnecting the O2-sensor set a trouble code or not?
Will disconnecting the knock sensor set a trouble code or not?

I have no spare ECM or PROM. Would like to make sure which of the two is bad before replacing.