Speedometer shows 120-220 mph idle high - ZR-1 Net Registry Forums

hpbadger · 03-02-2007

Did battery replacement and now idle is high 12-1500 and speedometer reads 120mpg at about 30mph and 220+ at 66mph. I will do paperclip and see what codes are there.

Anybody ever have this issue? Thanks!

hpb

03-03-2007

Probably no codes to display, unless you do have a SES light present.

Check simple things first.
Disconnect battery for 5 minutes and restart.
Prom fully seated.
ECM plugs fully inserted.

Did you touch anything else while doing the battery swap?

hpbadger · 03-03-2007

Quote:

Originally Posted by Jeffvette

Probably no codes to display, unless you do have a SES light present.

Check simple things first.
Disconnect battery for 5 minutes and restart.
Prom fully seated.
ECM plugs fully inserted.

Did you touch anything else while doing the battery swap?

I don't think anything else was touched. I checked to see if a vaccum hose got disconnected but didn't find any. Also, removed IAC and cleaned it and hole in throttle body.

Where is the ECM and prom located? Thanks very much for your help!

hpb

tccrab · 03-03-2007

ECM is the box on the drivers side firewall. Right next to the power brake booster.
It dismounts by removing the two bolts on the inside and just pivoting up. The PROM lives inside the ECM underneath a plate on the bottom.

Make sure the key not "on" when messing with the ECM.
Remove the negative battery cable as extra insurance.

TomC
'90ZR1 #792

hpbadger · 03-03-2007

Quote:

Originally Posted by tccrab

ECM is the box on the drivers side firewall. Right next to the power brake booster.
It dismounts by removing the two bolts on the inside and just pivoting up. The PROM lives inside the ECM underneath a plate on the bottom.

Make sure the key not "on" when messing with the ECM.
Remove the negative battery cable as extra insurance.

TomC
'90ZR1 #792

Thanks! Found ECM all plugs seem to be good. Removed battery and battery tray to get better look at connections in the area and vaccum lines. All vaccum lines look to be in order.

Battery was changed by shop which replaced rear surround after my accident. They did a wonderful job on the body ...hispeed customs in Tucson.

Car sat for a while (maybe 3 mos without starting).

I will check PROM and change the IAC today and go from there. If battery was dead and good battery introduced maybe exposed some weakness in the connections.

hpb

03-02-2007	#1
hpbadger Join Date: Sep 2006 Location: Tucson, AZ Posts: 25	Speedometer shows 120-220 mph idle high Did battery replacement and now idle is high 12-1500 and speedometer reads 120mpg at about 30mph and 220+ at 66mph. I will do paperclip and see what codes are there. Anybody ever have this issue? Thanks! hpb

03-03-2007	#2
Jeffvette Guest Posts: n/a	Re: Speedometer shows 120-220 mph idle high Probably no codes to display, unless you do have a SES light present. Check simple things first. Disconnect battery for 5 minutes and restart. Prom fully seated. ECM plugs fully inserted. Did you touch anything else while doing the battery swap?

03-03-2007	#4
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,654	Re: Speedometer shows 120-220 mph idle high ECM is the box on the drivers side firewall. Right next to the power brake booster. It dismounts by removing the two bolts on the inside and just pivoting up. The PROM lives inside the ECM underneath a plate on the bottom. Make sure the key not "on" when messing with the ECM. Remove the negative battery cable as extra insurance. TomC '90ZR1 #792 __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]