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92 pontiac sunbird blowing ECM Fuse...


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grand_sea
User

Jun 18, 2006, 9:43 AM

Post #1 of 8 (4676 views)
post icon 92 pontiac sunbird blowing ECM Fuse... Sign In

Original post (92 pontiac sunbird, ran out of gas now...
Car Repair Guides: Automotive Repair: General Discussions: )
The above was the original post which lead to the discovery of this problem!


I checked the fuses & the ECM(Emissions Control Module) fuse was blown! Replaced it & she fire the first crank(w/help from the jumper box)!! it took three fuses to get 15 miles But I got it home !!!

Any tips on what to start with in trouble shooting why the ECM Fuse is blowing intermittent??
R.G.
south central Minnesota


grand_sea
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Jun 18, 2006, 8:06 PM

Post #2 of 8 (4671 views)
Re: 92 pontiac sunbird blowing ECM Fuse... Sign In

Don't know if this is anything related but my fiance' just told me the horn started working a day or two before it died!!
R.G.
south central Minnesota


DanD
Veteran / Moderator
DanD profile image

Jun 19, 2006, 4:20 AM

Post #3 of 8 (4664 views)
Re: 92 pontiac sunbird blowing ECM Fuse... Sign In

The 10 Amp ECM fuse wiring leaves the fuse panel and splits off in three or four different directions depending on whether this Sunbird is a four or six cylinder.
On the four cylinders this fuse protects the ECM’s ignition power feed circuit, Fuel injectors and the ignition module. The ignition coils as well but they are connected internally of the module.
The six cylinder is almost the same except there is one more branch that splits to feed front and rear injector banks.
So the horn suddenly beginning to work is probably a coincidence or the Pink/black wire of the ECM fuse circuit has shorted to the horn circuit.
Does the fuse blow when the horn is pressed?
The hard part about finding you or what is the cause is that you need all three or four circuits connected to power for the engine to run and in your case even worse because the fuse doesn’t blow right away.
If the fuse would blow immediately after the ignition switch was turned to the run position; you could one by one disconnect the ECM, ignition module and injectors until the fuse held.
What you may have to do is cut the Pink/black wire close to these different units one at a time and feed that unit with a fused jumper wire.
For example while you’re feeding the ignition module with the jumper and the car quits after a few minutes. You check and the fuse panel fuse is ok, but the jumper wire’s 10 Amp fuse has blown. Now you know that the short to ground is in the ignition module or one of the coils.
If by chance after connecting all of the units to the jumper wire and the dash fuse continues to blow; start looking at the wiring harness, that pink/black wire may have rubbed through somewhere and is touching ground.
A process of elimination and a lot of patience find problems like this.
Dan.

Canadian "EH"






grand_sea
User

Jun 19, 2006, 12:03 PM

Post #4 of 8 (4660 views)
Re: 92 pontiac sunbird blowing ECM Fuse... Sign In

It is a 4 cylinder! and the horn wasn't used on the 15 mile trek so I also think it's a coincidence Thank you & I'll post back when I find the nasty short/prob.!!
R.G.
south central Minnesota

(This post was edited by grand_sea on Jun 19, 2006, 12:06 PM)


grand_sea
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Jun 20, 2006, 8:08 PM

Post #5 of 8 (4645 views)
Re: 92 pontiac sunbird blowing ECM Fuse... Sign In

I got brave and tried to recreate the conditions in which the fuse blows! I filled the gas tank, replaced the fuse & made sure I had plenty of extras! so I drove around town for 5 miles never going above 30mph stopped checked the fuse it looked brand new! then I tried to hit the hwy put the pedal to the floor & when I was up to 50mph it blow. Pulled over replaced the fuse. got up to 65mph for about 5 miles by just easing it! got pulled over!! opps! told the cop what I was doing and he told me to pick a different road(no ticket). any way to sum it up I was able to get up to 65 twice by feathering the pedal but popped it as soon as I hit the higher RPM's and about 50mph thought this might help !!! RG

P.s. I checked all the wires I could get to from the top they all look good! someone walked off with my ramps so I haven't got under it yet! also I found this weird! The fuses aren't burning clean like with a ground short! but rather it's leaving a black filament like ash! Don't know if it narrows things down but one can hope right!!
R.G.
south central Minnesota


grand_sea
User

Jul 1, 2006, 9:07 AM

Post #6 of 8 (4632 views)
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I finally gave up and brought it to a shop they unplugged the Cyl. #4 Injector. It stopped blowing fuses! they tested the injector and it's shorting out (of course this is the 1 thing I didn't test for) so now it's running off of three cylinders for about a week they had to order the injector!
R.G.
south central Minnesota


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 1, 2006, 12:33 PM

Post #7 of 8 (4630 views)
Re: 92 pontiac sunbird blowing ECM Fuse... Sign In

Just a thought to prevent more troubles. DON'T drive the car that way any more than necessary. One out of eight down is bad and one out of four is nasty, T



grand_sea
User

Jul 6, 2006, 5:45 PM

Post #8 of 8 (4625 views)
Re: 92 pontiac sunbird blowing ECM Fuse... Sign In

Ya it didn't mind going down hill, but, up hill was....well, ah, not fun when a truck was following! They replaced the injector this morning & did a few other things that I didn't ask for but were need things so I didn't complain! now it runs like a top! well o.k. it still run like a 4cyl. old sunbird but at least the tranny's still good( nock on wood)!
R.G.
south central Minnesota






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