voltage at idle
08-30-2017, 01:03 PM
#1
Registered User
Thread Starter
Join Date: Sep 2015
Posts: 87
voltage at idle
Hey Guys,
Getting different voltage readings at idle.
Autometer dash gauge reads 12.3
When I run a scan it fluctuates between 10.7 and 11.9
When I put a volt meter directly to the battery terminals it reads 14.6
Which reading is accurate? Car seems to turn over a bit sluggish sometimes.
The battery and all ignition components are all new. Any suggestions?
Getting different voltage readings at idle.
Autometer dash gauge reads 12.3
When I run a scan it fluctuates between 10.7 and 11.9
When I put a volt meter directly to the battery terminals it reads 14.6
Which reading is accurate? Car seems to turn over a bit sluggish sometimes.
The battery and all ignition components are all new. Any suggestions?
08-30-2017, 03:12 PM
#3
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,651
Re: voltage at idle
Battery will normally read the highest.
Scanner shows you the voltage at the PCM. There's voltage loss through (factory circuit described, yours will be different) red junction box, fusible link E, splice S200, ignition switch, connector C200, fuse #5, connector C230, a splice that splits the wiring to PCM pins B30 and D3, and the MAF sensor, and all the intervening wiring. Ground is supplied from G102 (stud at ICM/coil brcket) and G103 (on block above starter) I would take a good look at the PCM 12 volt wiring, and the grounds. 10.7 volts at idle is too low. You should see 12-13 volts at the PCM at idle, based on the 100's of data logs from healthy engines that I have looked at. An underdrive crank or alternator pulley can be a problem as well, depending on engine idle speed.
Gauge depends where you attached the wiring.
Scanner shows you the voltage at the PCM. There's voltage loss through (factory circuit described, yours will be different) red junction box, fusible link E, splice S200, ignition switch, connector C200, fuse #5, connector C230, a splice that splits the wiring to PCM pins B30 and D3, and the MAF sensor, and all the intervening wiring. Ground is supplied from G102 (stud at ICM/coil brcket) and G103 (on block above starter) I would take a good look at the PCM 12 volt wiring, and the grounds. 10.7 volts at idle is too low. You should see 12-13 volts at the PCM at idle, based on the 100's of data logs from healthy engines that I have looked at. An underdrive crank or alternator pulley can be a problem as well, depending on engine idle speed.
Gauge depends where you attached the wiring.