Regarding 1993 Camaro LT1

Without getting into the whole story......

My question is.....what actually triggers the code 26?
Is it the PCM? Or the remove able MEMCAL?

 

The 93 ECM has quad-driver modules that drive high amp loads. DTC 26 is for the module that drives the AIR pump relay, the EGR solenoid, and the EVAP solenoid. While the code could be set by failure of the module, a more likely cause is a problem with the electrical circuit for one of those devices.

The most frequent cause is a blown fuse for the AIR pump.

An aside - "PCM" (powertrain control module) applies only to 94 and up, where the computer controls both the engine and the transmission. 93 controls only the engine.

 

I swapped my aftermarket prom out with my older one and it cured the engine light... I just did it a couple hours ago. I had already gone through the diag got my drivers to each component....even though I no longer run an get it air pump. I also swapped in an extra ECM I had but that didn't fix it. Only until I swapped the PROM did it get rid of code 26.

That's why I was asking what actually trips code 26....the ECM or the PROM


thank you

 

Was it a stock prom, or a revised program prom? Diagnostics can be programmed out. The conditions that have to be met to run the diagnostic are part of the program, and the condition that trips the code is part of the program. It's all in the prom.

 

Correct. It is a prom from TPIS that uses the original prom for a piggy back. But I guess something went wrong with the prom bc it was ok when it was new.....and right now I have the original prom with an older aftermarket prom on it and it doesn't trip the code.....

I hope they help me out with getting me a new one. It's only 2 years old an for $600 and such a stupid reason for failure I hope they send me a new one....

 

I called TPIS just now and I was told it is not likely the adapter chip they sold me bc the software they programmed is not changeable. I asked him could that leg of the software be corrupt. Basically I was rudely told there is nothing wrong with the chip. He said to send it in and they will check it.

 

I don't think you understood what Fred typed. It's possible the old prom is programmed to ignore that code and the new one isn't. If so, the code is new and the new prom is letting the ecm tell you about it. Maybe have them check the old one for modifications, if they haven't already.