After having new hangers welded on the exhaust system yesterday the car wouldn’t start on its own. I had to push start the car. I thought the battery was run down. On the way home from the muffler shop I noticed the speedometer wasn’t working anymore. Now when you try to start it the cooling fan runs but the started doesn’t engage. Could have an electric welder cause this?

 

I highly highly doubt that's what happened. It's more likely they knocked a ground loose somehow....which is also unlikely. beyond that I have no idea.

 

Was the negative battery terminal disconnected when they were welding?

 

No they didn't disconnect the battery.

 

Well, it's always a possibility that something was shorted out.

When ever welding something on the car, I always disconnect the negative just in case.

 

With the advent of most and more sofisticated ECU's in cars these days, massive electrical shocks into a system can cause problems everywhere.

Rules like unplugging the ECU and leaving the battery connected are set for a reason (battery helps dampen any electrical shocks). They also sell clamps for the battery to put in place during welding as well.

Was this a wellknown shop that has insurance? You might want to talk to them about this and bitch.

 

yessir. Running voltage/current to your cars source for ground is not good.

 

The repairs were done at a local independent muffler shop.

 

I have personally seen what welding on a vehicle can do to its electronics.

Welding can cause shorts and intermittent faults in your ECM if the ECM is not disconnected before hand.

I suggest that you go back to them and demand that they pay to get your car fixed. It was from their gross negligence that your car is now inept.

 

ECU.. tisss

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDM-Civic-Hatch &raquo;</TD></TR><TR><TD CLASS="quote">ECU.. tisss</TD></TR></TABLE>

fyi, Honda/Acura refers to is as the ECM or PCM

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DirtySol &raquo;</TD></TR><TR><TD CLASS="quote">fyi, Honda/Acura refers to is as the ECM or PCM</TD></TR></TABLE>

Both ECM and PCM are ASE standards, ECU was the old standard.

Does the ECM even control the starter output on that car? It doesn't on some honda's. What is your car?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by krustindumm &raquo;</TD></TR><TR><TD CLASS="quote">

Both ECM and PCM are ASE standards, ECU was the old standard.

Does the ECM even control the starter output on that car? It doesn't on some honda's. What is your car?</TD></TR></TABLE>

SAE

Honda has always referred to the control module as either a PCM or ECM.

the starter relay on all fuel injected Honda's is controlled VIA a grounding circut in the ECM/PCM

 

whooops, need to proof read better

my civic cranks w/o the ECM hooked up, i believe.

 

Yes, it's possible that the damage was caused by the welding. Electricity takes the path of least resistance. If that was through your ecu, then it likely burned it up....then found the next least path of resistance. It's possible that it did this more than once till it found a path that could carry the power needed to weld.

When welding the exhaust or anything on the car, your ground should be attached close to the weld. In other words, if you're welding on the exhaust pipes, put the ground to the exhaust pipe, not on the body of the car, not on the body of the car where it must find a good path to carry the current. Grounding to the battery or the ground cable would NOT be reccomended.

Of course the shop likely knows to put the ground close, but just neglected to do it....so if you ask them they will probably lie about it.

 

I wanted to make sure that it wasn't just a coincidence.
I’m using a Hondata ECM and a s200

 

My main cars have ECU's They are also 15+ years.. so that might have something to do with it

 

The starter will not engage with a 40 amp boost from the charger.

 

When I first started working at the body shop as an apprentice, I was welding on a Mercedes SL600.....ended up toasting the ECU because I didn't disconnect the battery......I was 17, and needless to say, I didn't work there very long. Always disconnect the battery when welding on a car. They also make a box with two jumper cable clamps on it, I thinks its some kind of surge protector, that one hooks up across the battery terminals, and it is supposed to protect the electronics when welding. I like these better than disconnecting the battery, because half the time you've got to search for some stupid code to reset the radio.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DirtySol &raquo;</TD></TR><TR><TD CLASS="quote">

SAE

Honda has always referred to the control module as either a PCM or ECM.

the starter relay on all fuel injected Honda's is controlled VIA a grounding circut in the ECM/PCM

</TD></TR></TABLE>

you guys r so picky, i think everyone refers to it as an ECU

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by m R g S r &raquo;</TD></TR><TR><TD CLASS="quote">

you guys r so picky, i think everyone refers to it as an ECU </TD></TR></TABLE>

I am just being the typical Honda/Acura technician.......everything has to pronounced correctly and the correct abbreviations are to be used to avoid confusion around the shop.

 

I would like to mention that 2 nights ago my cat heat shield cranked off at one weld joint, so I welded it on the car. No damage or anything, but then again... its an older car.