eddie jr

Ok, I was hoping some of the TPS wizzes could help me out with this problem. I just adjusted the TPS. It WAS at 0.77V at idle and is now at 0.545 and 4.22 at WOT. THe only problem is that now I have a code 21 set, Why would this be AFTER I adjusted it to factory spec?? What exactly does the 21 mean (there wasn't much detail in Haynes)

THe other question is why didn't the SES light come on, yet the code was set??? I thought the light was always supposed to come on??

thanks,
eddie.

Ovrclck350

That's probably a code thrown a long time ago, but did you try resetting the computer? You always should with any major change, especially with electronics.

Code 21 is High Voltage from TPS. It's probably still there from your previous setting.

Disconnect the negative battery cable for 5 minutes, then reconnect, run a while, then pull the codes. Betcha it will be gone.

Gumby

The book says you need to disconnect the postive to clear the codes. But allways pull the negtive first. and put them back in in reverse.

Matt

Ovrclck350

Where did you read Positive?


I've AlWAYS read the negative. There is NO reason at all you would need to disconnect both. Once there's no power, there's no power.

I'd think however, if the ECM still had power left in the line (yes, I've seen weird things happen with cars) and the cable grounded out (the positive) it could screw things up. The negative cable grounding against anything wont' hurt anything.

Gumby

Sounds funny don't it. It is a haynes book but it say either dis connectthe postive[ they should tell you to unhook the neg first as you could blow your self up] or disconnectthe power pig tail for the ECM near the batt and looksl ike its kinda under the coolant over flow.

Only reason I remeber it as its sound funky, but why it may take 5 min if you just disconnect the negtive. All the power needs to drain of the system. Kinda like unpluging a VCR, if only for a min , it will remeber its settings, wait to long and you gotta re-do them.


Matt

eddie jr

ok, that makes sense because I didn't check codes before since there was no SES light. I will check for codes again today and see since I disconnected the battery after doing the timing.

Is that right though that a code can be set and the SES light not come on??? It came on when adjusting the timing (EST bypass disconnected), so why not with the TPS??

Nixon1

That is kinda weird...I dont imagine you throwing a code without that light. But then again...computers can get weird... My car will throw a light if I disconnect the EGR valve sensor...but if the EGR valve is malfunctioning badly (not opening AT ALL), it wont flash a light. It also wont flash a light for my O2's whatsoever, and it wont flash a light if I disconnect my IAC valve. Fords suck.

PS-Like they said, just disconnect the negative for a few minutes. It'll be enough to reset the computer. Power can't travel unless it has a ground in these systems. You disconnect the ground and you kill the feed from the positive side. Disconnecting the ECM fuse is an equally easy way to do this though, and it doesnt reset your CD player. The ECM fuse is mounted to the passengerside fender, in the engine bay. It's encased in rubber..lift the top off and you'll see a fuse in it. Just yank it for 5 mins.

eddie jr

overclck350 - yeah, you were right, it must have been an old code cuz I checked again today and there was nothing Youwere saying it was a high voltage error though. Do you know the value over which it becomes too high??

Also, is 4.22V too low for WOT? I thought I read somewhere it should be 4.5V.

TomP

The book says 4.50 volts for WOT but it's impossible to set, the ECM goes into Power Enrichment mode at something like 80 % above idle voltage, so it's okay. Highest I got out of mine for WOT was 4.25 volts.

eddie jr

ok, cool, thanks TomP.

camaro_junkie

First of all, thanks for the idea about the ECM fuse. I hate having to reset my stereo. Also, I'm not saying you're wrong, but my car always resets the codes when I only disconnect the neg bat cable for a second. It may just be that you are guaranteed to have them reset if you wait a little. It might happen sooner.