What up?! So I'm having a few more issues with my truck you experts might have the answer to.

A few days ago, just after putting in my ultra gauge, the SRS light goes on. I read a few post on it, clean some connections, clean out the buckle, check wires, move seat back and forth, etc. Went out for about a day but came back on. I also read a low battery voltage might be the issue as well. Had it checked by autozone and told me it wasn't the battery but the alternator ready to go...which I had rebuilt about a year ago. According to the ultra gauge the battery voltage averaged between 13.4 to 13.8 but would sometimes be as high as 14.1. I guess it should be within the range of 13.6 to 14.4 or so. Then today I get a p300 and p303 code.

As far as the drive, it appears to run perfect, no change in anything. I sense no difference in power, misfiring, nothing.

2001 Discovery 147K. New head gasket, plugs, wires, and coils about 2k miles ago. New battery and rebuilt alternator about a year ago.

Questions.

Is it possible for low battery voltages to cause the SRS light or even a misfire?

Should I start by replacing/rebuilding an alternator that I had previously rebuilt?

What other things should I check for, specific fuses or wire/ground connections?

Are any of these problems related?!

Thanks again, appreciate all the help!

 

your voltage look good to me, but for some reason you have a misfire on #3, you my try switching the plug and wire and see if the misfire travels also.

 

Add some grounds to the engine bay and connect with your neg terminal. I had more or less the same issues and this fix resolved all of them.

 

Just like with the Three Amigos for the ABS or the flashing M+S lights that indicate a problem with your trans, it's important to get the SRS codes read. Otherwise you are just shooting in the dark.

In my case last spring there was a short in the wiring harness connector at the SRS module. Getting the codes read will tell you whether it's a problem with circuit for one of the airbags or for the pre-tensioner's or something else.

Diagnose, diagnose, diagnose.

And by the way, I don't think there's any reason to think it's the alternator.

 

Hey all thanks for all the good advice.

So I took it to the alternator shop that rebuilt it, they tested and said all is well with the alternator. The exact opposite of what autozone said which they claimed was the problem. As far as I'm concerned it's a wash and assume both battery and alternator is good. After all, I never did get a low voltage light, I'm just reading off the ultra gauge. As for the SRS, I'll just have a local shop read the codes to narrow down the issue. I'll let you know what they are shortly.

I'm beginning to think these are all separate issues. Still wondering why I got a misfire code, it hasn't popped up in a couple days now...I'm sure it'll be back.

 

I dont know who you are
But I will find you. and I will hug you.

 

I was thinking the same thing. When I swapped my engine I boogered the grounding strap (connects at LH rear of engine) and had some odd things like that going on until i figured it out. The OP's head gaskets were done, so it is possible that the strap isn't in good contact on one end or the other.

 

Is that what it was, a grounding strap?! I had no idea what that was for, or electrical related for that matter. I guess it is possible that I loosely attached, or maybe not at all hmmm.

Can y'all elaborate more specifically on adding grounds and attaching to my negative? And will this fix essentially duplicate what the strap did?

Thanks again

 

My issue was misfires and the Powertrain Control Module (PCM) was throwing a code. I consulted with some wrenchers I know and they concluded that there is a lack of grounding throughout the engine bay (more specifically, a lack of electrons making back to the battery).

Maybe try getting a hold of some electrical sprinkler wire (or in my case, electrical dredge wire) and connecting them to solid grounding points throughout the engine bay. Then take the end of that wire cluster and solder then end into a big enough wire connector that can mount to the neg. terminal. Be sure to mount them away from pulleys, belts, etc., and button them up nice and neat. I'm interested if at least a few of those issues resolve themselves.

I'm not too experienced with car wrenching, but my friends are aces at this kind of stuff. And they immediately recommended this fix after having seen my issues.

 

The negative terminal of your battery goes a couple of places then attaches at the front right of the engine, just below the alternator. The ground strap is at the rear left, just behind the heads. The bolt at the front and the nut (over a post) at the back are generally afterthoughts, but without then you can have a lot of amperage running in odd places, trying to find a way to to ground.

If you were going to run extra grounds as suggested above, there is a good spot between the battery and the fuse box where the ground wire is bolted (if memory serves... I am not looking at it now). I think it is right behind the battery box or the box for the jack. I'm not an electrical guy but what is where I have grounded extra projects like offroad lights.