Voltage differs from DM to Voltmeter
- Thread starter TYTILIDIE
- Start date
Daron
Active member
Re: Voltage differs from DM to Voltmeter
I documented a voltage reading difference years ago, when I compared ECM B voltage levels to what is reported by the ECM. Some ECMs I tried varied as much as 2 volts. I would monitor ECM B voltage at WOT and then compare it to your Datamaster reading at a convenient RPM.
TYTILIDIE said:
I documented a voltage reading difference years ago, when I compared ECM B voltage levels to what is reported by the ECM. Some ECMs I tried varied as much as 2 volts. I would monitor ECM B voltage at WOT and then compare it to your Datamaster reading at a convenient RPM.
TYTILIDIE
METH HEAD
Re: Voltage differs from DM to Voltmeter
I would think that if the voltage varies in the ECM its going to make the truck run different. I know that I still have the same ECM i had last year and it used to be 13.5 in WOT runs. Ild just think it would make a difference in things.
I would think that if the voltage varies in the ECM its going to make the truck run different. I know that I still have the same ECM i had last year and it used to be 13.5 in WOT runs. Ild just think it would make a difference in things.
cloneman315
Active member
Re: Voltage differs from DM to Voltmeter
i ran a direct wire from the batterey with a relay right to the ecm like turbo 6 had and i picked up almost 2 volts
i ran a direct wire from the batterey with a relay right to the ecm like turbo 6 had and i picked up almost 2 volts
Tooky
Serious about performance
Re: Voltage differs from DM to Voltmeter
Good idea to test with the fan off. Reason I mention is because a local Syclone here has the same issue, and it's only since he installed the electric fans.
When I added my alcohol injection, it also lowered my ECM voltage from about 13.1 to 12.6-12.8 at WOT but didn't seem to have any adverse effects. I'm still going to try that "ECM direct power wire/relay" trick they mentioned, and see if it improves performance any.
Good idea to test with the fan off. Reason I mention is because a local Syclone here has the same issue, and it's only since he installed the electric fans.
When I added my alcohol injection, it also lowered my ECM voltage from about 13.1 to 12.6-12.8 at WOT but didn't seem to have any adverse effects. I'm still going to try that "ECM direct power wire/relay" trick they mentioned, and see if it improves performance any.
mrweelr
New member
Re: Voltage differs from DM to Voltmeter
The alternator to ECM B fuse booster wire was one of the first "free" mods I did to my truck. Made a BIG difference in the voltage the ECM/Datamaster was seeing vs. cigarette lighter. It's an easy mod to do, just be sure you fuse the booster wire just in case.
The alternator to ECM B fuse booster wire was one of the first "free" mods I did to my truck. Made a BIG difference in the voltage the ECM/Datamaster was seeing vs. cigarette lighter. It's an easy mod to do, just be sure you fuse the booster wire just in case.
George Blake
DONATING MEMBER
Re: Voltage differs from DM to Voltmeter
I've done the electric fan deal and can verify that the stock 105 amp alternator does not like the electric fans. :tdown:
I've done the electric fan deal and can verify that the stock 105 amp alternator does not like the electric fans. :tdown:
mrweelr
New member
Re: Voltage differs from DM to Voltmeter
Here you go:
http://www.syty.net/forums/showthread.php?t=266&highlight=voltage+fix
Here you go:
http://www.syty.net/forums/showthread.php?t=266&highlight=voltage+fix
Daron
Active member
Re: Voltage differs from DM to Voltmeter
Doesnt sound like the fans are your voltage problem. I might have missed it, but are your voltage readings ECM reported, or are you using some form of voltmeter on the ECM B feed?
If your ECM B voltage is actually 12.6 as measured with a good voltmeter, then I would consider addressing that with the suggested mod, but if it is 13ish-14volts, I would look to remedey your ecm voltage issue elsewhere (ie. ECM).
TYTILIDIE said:
Doesnt sound like the fans are your voltage problem. I might have missed it, but are your voltage readings ECM reported, or are you using some form of voltmeter on the ECM B feed?
If your ECM B voltage is actually 12.6 as measured with a good voltmeter, then I would consider addressing that with the suggested mod, but if it is 13ish-14volts, I would look to remedey your ecm voltage issue elsewhere (ie. ECM).