I have a self powered continuity tester. If I connect the clip to a good ground, when I probe another ground it should light up if that ground is good correct? What about a sensor? If you have a ground wire from the sensor, if theground is good then will the tester still light?If that's correctthen would a no light indicate the wiring and/or sensor is bad, or just the wiring? Sorry for all the questions, I'm just trying to get a handle on testing for good grounds.

Thanks

 

ur on the correct path if its a "ok" ground, it will beep, that doesnt mean its "good" nessarily to check for a good ground put ur meter on DCV and take ur red lead to a hot <fuse box>, and ur black to the ground...that ur checking should get around 12-14 volts also what kinda of sensor areyou checking...


this is how i do it, there are other ways to check grounds too

 

It would mean the wire is has a break, or is no grounded at the other end properly.. Sensors don't send out grounds. The send out (+) voltage. They use the ground as a reference. On the other hand, if you're testing, say a wire after a relay, that reads ground when the relay is engaged, and the relay was bad, then that wire would not read ground. But the wire wouldn't be bad, it would be a relay.

In short, there is no one answer for your question, there are multiple scenarios.

 

ok, lets get some things straight here.

Are you using a light-up meter, an analogue multimeter, or Digital multimeter?

when the 2 leads have continuity between them on a AMM or DMM, either should read 0, for 0 ohms. If there is a break, they will either display the number of ohms between the leads, or 1 for a broken line, or no continuity.

on a light up one, i honestly am clueless. Never used one (except for a voltage test light). I always use a DMM.

 

he said what he is using in his post never seen a powered test light...kinda defeats the purpose

 

I have a Blue-Point light that does that. It plugs into the cig lighter of the vehicle. If you touch a ground, it lights green and beeps, if you touch (+) it lights red and beeps.

It's really handy because it's safer on sensitive wires like data and BCM wires. If you probe a wrong wireit isn't gonna toast the BCM like it might if you had the other end of a regular test light on 12V and probed a wire that was meant to be ground from a BCM or something.. And you can use it to test tach as well. The light will flash back and forth from green to red and the light will beep really quick and the beeps will increase with RPM.

 

I'll see if I can answer all the questions in one post. The sensor I was in question about is the speed sensor ground. I was checking at the pcm connection. That particular one is connector 2, cavity 25. It's actually the tranny output sensor, but on the pin out it just says speed sensor. I unhooked the connector from the pcm, and then probed the cavity. What got me curious about it is there are 3 other grounds on connector 1, they are cavity 4, 31, and 32. Cavity 4 says it's the sensor ground, and 31 and 32 just say ground. Again I unhooked the connector and probed the cavities, and all three of those make my tester light up. So when the speed sensor ground didn't make it light I got curious.

The tester is just called a self powered continuity tester. It has a battery inside and lights up when you have a closed connection. I think the purpose to it compared to a normal test light is sort of like what rtkota5point9 is saying about his. I'm not sure how many volts a single AAA battery sends out, but I'd think it's less than 12. I have two DMM also, so maybe I'll just probe with those.

 

The speed sensor IS a ground, but not a constant ground. It pulses ground as the truck is moving. I can't remember exactly how many pulses /per revolution it is. You can test that wire just like you're doing, but you need to jack the truck up and put the truck in drive and let the wheels turn.

Having somone turn the wheels by hand wont work unless you've got 2 people, one on each wheel, otherwise the diff will just turn the other wheel the other way and not the drive-shaft.