Vp Special K

Anybody know why my cruise control light , lights up when i step on my brakes?

ChiBoy

What car?

Did you swap clusters?

Did you change computers?

Vp Special K

94 cx with a d16z6 swap

yeah i switched gauge clusters with an si gauge with the rpm tach

right now im running the p28 ecu

ChiBoy

Is the p28 a manual or automatic ECU? If it's a manual, is it originally a manual, or was it converted frm an auto ECU?

Vp Special K

well the guy i bought it off from said it was from a manual , but is there any way i can make sure?

ChiBoy

I had a similar problem with my 93 CX, but not with the brakes.

Part of the problem was that my CX had a "shift up" light in the cluster. When I switched my cluster for an EX cluster, the cruise control light was connected to the same place as the "shift up" light. So whenever the "shift up" light went on, my cruise control light would go on. The "shift up" light is connected to pin D18 on the stock CX ECU.

The automatic P28 ECU uses pin D18 for part of the safety interlock system for the automatic transmission. I'm not sure how that system works as far as how or when is would supply voltage to D18, but if it did, the light (cruise control) would light.

I could only guess, but I wonder if the ECU you bought was originally an automatic. Open up the cover of the ECU and look for the bank of resistors in the corner like the ones in the picture. Look closely at RP17 and RP18. Is RP18 a resistor with a single black line or a piece of wire? Is the little white square at RP17 clean and white, or is there a little brown mark like a resistor used to be there?

Post back what you find.

Also, does your car have cruise?
Have you tried running the stock CX ECU?

toolbox

haha I had the same prob. EX cruise light acting like a shift light.

If your car doesn't have CC just take the bulb out.

ChiBoy

Hey Special K! Any news?

Vp Special K

I still couldnt find out why it was still doing it but it didnt seem like it was doing any damage so i just left it the way it is. Could this problem be caused by an idle problem? because lately ive been having an idle problem from a broken tps , but i havent had time to replace it so i'll let you know when i do that.

....thanks for all your help

Ass_Clown

I had the same problem when I put an auto p28 in my car. I'm guessing it's something to do with the ECU being auto. I also had idle problems when I used that ECU.