can all car modules cause a short circuit? test light stays on unless i unplug every single module?

[kassem999999999]

can every single car module cause a short circuit? my test light stays on between batt and terminal unless i unplug every single module? any advice?

 

[DPG]

What points are you testing between? And be careful using a test lamp - a multimeter may be safer and give more informative results.

Oh and welcome to the forum!

 

[kassem999999999]

What points are you testing between? And be careful using a test lamp - a multimeter may be safer and give more informative results.

Oh and welcome to the forum!

im new to this issue.i suspect a short circuit in my car so i have my test light between negative terminal and negative battery post. the test light does come on indicating a short. so i have been pulling fuses to find the culprit however every one of my circuit is showing a short unless i unplug the module or accessory its connected to. its as if every module is allowing continuity from power to ground. is there a better test i can do to find out whats going on, can one short be causing the whole car to look like its all shorted out?

 

[DPG]

No !! A test lamp will always light if connected between battery positive and negative. That's not a short.

What are your fault symptoms?

 

[kassem999999999]

No !! A test lamp will always light if connected between battery positive and negative. That's not a short.

What are your fault symptoms?

no i have it connected between battery negative and negative terminal that goes to ground. so test light is not touching any positive at all but still lights up.

 

[DPG]

Right. I'm still not sure why you are testing like that. What fault symptoms is the car showing?

 

[kassem999999999]

Right. I'm still not sure why you are testing like that. What fault symptoms is the car showing?

because my body control module and some others is not communicating with my car pcm.so im not able to program the car's ecu. but i find it hard to believe that all these modules are bad so i feel like my testing procedures are not correct.but if test light coming on with just negative side connected, wouldn't that short have to be located?

 

[DPG]

because my body control module and some others is not communicating with my car pcm.so im not able to program the car's ecu. but i find it hard to believe that all these modules are bad so i feel like my testing procedures are not correct.but if test light coming on with just negative side connected, wouldn't that short have to be located?

I can't believe they are all faulty no. What fault codes do you get from the system? You can't really rely on a test lamp here.

 

[kassem999999999]

I can't believe they are all faulty no. What fault codes do you get from the system? You can't really rely on a test lamp here.

yeah i think my testing is wrong. i was watching youtube and it said if your test light comes on between negative terminal and negative batt its a short. but my fuses don't burn so i think i wana start over here. so basicley my car was in a accident and i had to replace the damaged pcm.but to program it , it needs to synchronize with other modules like the bcm. the shop that tried to program it told me he thinks theres a short between the body control modules and the pcm but all wires are connected and no fuses are burning.

 

[kassem999999999]

Right. I'm still not sure why you are testing like that. What fault symptoms is the car showing?

i confirmed that my fuse box is getting ground and voltage . Does that confirm a short?

 

[DPG]

i confirmed that my fuse box is getting ground and voltage . Does that confirm a short?

Testing between which 2 points?
Are you having problems with battery drain?

 

[kassem999999999]

Testing between which 2 points?
Are you having problems with battery drain?

In my fuse box i tested between 2 positive fuses and test light comes on . also i tested between battery positive and battery negative and im getting 1.7 mega ohms. i don't have any burnt fuses

 

[DPG]

In my fuse box i tested between 2 positive fuses and test light comes on . also i tested between battery positive and battery negative and im getting 1.7 mega ohms. i don't have any burnt fuses

Which 2 fuses? And was there power to those 2 circuits at the time?

And was your battery disconnected when you measured 1.7M between positive and negative at the fuse box?

 

[kassem999999999]

Which 2 fuses? And was there power to those 2 circuits at the time?

And was your battery disconnected when you measured 1.7M between positive and negative at the fuse box?

yes battery was disconnected and i tried multiple fuses where test light lit up . between pcm fuse and horn, fuel pump, ac clutch, when i scan my car, it does communicate with pcm and lots of other modules. but no start

 

[DPG]

yes battery was disconnected and i tried multiple fuses where test light lit up . between pcm fuse and horn, fuel pump, ac clutch, when i scan my car, it does communicate with pcm and lots of other modules. but no start

Randomly testing between fuses will be confusing. You will get different results depending on whether each circuit is live or not.

If you got such a high resistance at the fusebox then there is no short between positive and negative. To be honest if there was a short like that you would be seeing blown fuses and/or melting wires.

 

[kassem999999999]

Randomly testing between fuses will be confusing. You will get different results depending on whether each circuit is live or not.

If you got such a high resistance at the fusebox then there is no short between positive and negative. To be honest if there was a short like that you would be seeing blown fuses and/or melting wires.

lets say i suspect a circuit is bad , how can i test that specific circuit for a short? im following a mitchel diy guide and its telling me if my transmission harness has less then 10k resistance between harness and ground that i have a short, and my reading was 0.3 for for that specific wire.

 

[DPG]

lets say i suspect a circuit is bad , how can i test that specific circuit for a short? im following a mitchel diy guide and its telling me if my transmission harness has less then 10k resistance between harness and ground that i have a short, and my reading was 0.3 for for that specific wire.

Is that referring to testing CANBUS lines to ground?

 

[kassem999999999]

Is that referring to testing CANBUS lines to ground?

no its transmission range sensor to ground. also do you know if that 1.7 m ohms means anything between positive and negative cable no battery connected?

 

[DPG]

no its transmission range sensor to ground. also do you know if that 1.7 m ohms means anything between positive and negative cable no battery connected?

But I thought the 1.7M was between positive and negative of the fusebox?

If you get an incorrect reading between transmission sensor and ground, have you tried unplugging it?

 

[kassem999999999]

But I thought the 1.7M was between positive and negative of the fusebox?

no the 1.7 is just between the positive and negative cable, i just tested my test light between 2 fuses on the fuse box with out ground connected to test lightand it lights.

 

[DPG]

no the 1.7 is just between the positive and negative cable, i just tested my test light between 2 fuses on the fuse box with out ground connected to test lightand it lights.

Sorry but I think we're going round in circles here. I'd recommend an auto electrician has a look. One with a decent code reader and knowledge of fault finding.