Hello everybody. I am Nico, live in the south of Spain, drive a C4 Corvette 1984 CFI, an old military landrover 88 and a tin can with wheels (Audi 80)
I am a mmber of the VCorvette forum as well, but very few people ther with a 1226026 ECM
I have a problem with my Corvette. The ECM is an 1226026. The TCC will lock at approx 20 kM/Hr and remains until I slow dow below that speed. The TPS is calibrated ok, the scan (WINALDL) does not show strange things (perhaps it does when someone points me to a place to look at)
TCC does not lock in open loop. The brake pedal switch works ok
I did test the TCC locking also with a 3 Watt lightbulb from pin F to the +12V
It confirms that.
The TCC lock seems only depending at speed, but I did test very briefly.
The problem is that, when slowing down, the car tries to pull away at approx 700 RPM when close to 15 Miles/hr. So the drivability is bad. At high throttle, the car runs very fine. I have to find if I can make the TCC unlock at high throttle, but I donīt think so.
Can someone please help me where to find that problem? Or repeat the test with the lightbulb so I know when the TCC should come lock?

 

I had this problem with one of my cars where it would engage very early, and I think it was something in the ecm. Being cheap, I just wired in a relay by the ecm using the 4th gear switch output from the trans so the TCC wouldn't engage part throttle unless in 4th gear. I also used a micro-switch on the carb linkage so it would engage under WOT in any gear.

 

Thanks for the reply.
So this fault IS possible in the ECM. I considered it quite weird, so I was concentrating at the inputs mainly, but canīt find anything. The fact that you had it as well really does help me.
I understand your solution, clever.
I did something similar, but not auomatically. Because I drive quite a lot low speed in traffic and in the vilage, the drivability with the early TCC was really bad. I wired in a switch next to the gear switch lever to switch OFF the TCC when driving traffic.
But I guess I will look for an other ECM. I love how it was and I donīt drive track, there is none here in Spain. Just at the moment when an other car will try me , I like to smoke them

 

This was a common problem with 84's. It is known as "chugging". GM produced a new prom to fix the problem. With the 6026 your only choice is to change the prom. Aftermarket chips like Hypertech and ADS will fix the problem. I may have one lying around that I am no longer using. Drop me a email @ azc4vette@***.net and we an go from there.