Jim5pt7v8

Here's an odd question but for the 10 years I've owned my vette I've never seen the "Upshift for best economy" light come on. I've always assumed it was there only for the manual tranny. However I just recently completed front and rear suspension rebulid and when I was done I went out for some spirited driving and, woah. There was the light! My question is what could I have done since the suspension can't have anything to do with this. The only other thing I can think of is that I reconnected a tube that had cracked off. Maybe that controlled the light? The tube was on the driver side under the upper control arm. It was under the alignment bolt closest to the front of the car on the head side of the bolt. About a 1/4 inch diamater. If that makes sense.

The second part to this question is, how come sometimes the light comes on with the up arrow and says "upshift" and other times it comes on with the up arrow and says "upshift for best economy"?

Pete K

If the shifter is in the OD position, it could be a failure in the lock up curcuit. For some reason, failing to lock the converter seems to trigger it.

Jim5pt7v8

It appears to be working correctly. If I leave the car in 3rd for a little extra power it will come on if the throttle is light and above 2000RPM or so. Once I shift to OD then it shuts off. I am just wondering some more detail on it.

Pete K

I misunderstood. I thought it was throwing the light more often than normal. Your sounds like it behaves just like my 87's. I never knew the specifics of what exactly triggers it.

Jim5pt7v8

The question is why did it all of the sudden start working??

Pete K

I am curious myself. I will try to dig my Helms book out of the attic tomorrow and investigate it.

Aggravated4life

My former 86 used to do the same thing if left in D too long.Maybe after some work you did,you "fixed" the problem or some loose connection.
Sounds like its working fine now!

ozvette87

I also thought that light was purely for manuals???? what exactly did you do to get it on? i think i know the tube you re-connected, i re conneected this on mine too but ive never had the upshift light. but now i have the urge to try an get it to light up.

CorvAdel

The tube you reconnected seems to be the charcoal cannister return line to the fuel tank...
To my knowledge this is totally independent to the up-shift light function..
That light comes on in my car about 55mph in D...it's telling me to go to OD, so that me and my car are more ecolicious..!!

86PACER

Mine comes on, but only the "Up shift" and arrow lights up. The words just below that "For Best Fuel Economy" stay unlit.

rick lambert

This is really funny, both another guy and I were having the same problems, 87 auto, and the upshift light would come on....mine even would come on sitting in Park last conversation we had, he for some reason changed his fuel pump....said his quit comming on. You know what's funny...my fuel pump died, so I replaced it...I have no clue, but mine quit comming on also. I know...wierd. Oh, I also discovered bare wires (insulation shrunk back 1-2 inches on my FP relay..fixed that at the same time).

morgan_kane

Same here.

87vette

Mine used to have Upshift for Best Economy lit up... now it just shows like you have described.

86PACER

So is there a seperate bulb for it?

scorp508

The "FOR BEST ECONOMY" only lights up during the power-on cycle of the dash. After that it is just "UPSHIFT". The times the light turns are on calculated by using TPS, RPM, and time values in the ECM. It is programmable if you have the chip redone. I can give you the stock #s for an '87 when I get home if you are that interested.

86PACER

Why?

scorp508

Hopefully because GM realized it was a lame light to have in the first place. The 4+3's automatic overdrive engagement in 2nd gear after light throttle from 1st to 2nd shifts was the predecessor to the ZF6's CAGS system.