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1995 Dodge Intrepid ECM fuse blows after driving short dist

Tiny
ECLECTIC
  • MEMBER
  • 1995 DODGE INTREPID
Computer problem
1995 Dodge Intrepid 6 cyl Front Wheel Drive Automatic. 3.3 liter. 165,000 miles.

ECM fuse blows after short drive with A/C cooling on sometimes?
All cooling fans are operational. No codes other than code 12 & 55 ring out on dash board. I installed a circuit breaker (20)amp in place of the fuse for the PCM.

I did find a wire loom behind intake manifold had got too hot & melted insulation but repaired that. I am not sure of what it went to exactly--- wiring harness that is--I will have to trace it down.

I drove over a hundred miles with A/C cooling mode in OFF and it runs WITHOUT blowing the PCM fuse.

Could the A/C transducer be shorting the ECM since I see on the shop repair manual it is one of two input to ECM (PCM)from the A/C circuit? No other fuses are blown and they are the correct amperage rating. PCM fuse raing 20 amps.

There are two main components that feed from the A/C circuit to the PCM (1) the A/C relay and (2) the evap transducer. Would the A/C relay more than likely cause an excessive amp draw if the coil was bad-or going bad----thus causing the PCM fuse to blow? What components would most likely cause an excessive current(amperage) draw to the PCM. It is an intermitten short when the A/C is in the cooling mode? Is there something I am overlooking on the wiring schematic?

Thanks
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Tuesday, May 11th, 2010 AT 9:51 AM

7 Replies

Tiny
MERLIN2021
  • MECHANIC
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Could also be the a/c clutch coil. test the relay like this:
https://www.2carpros.com/how_to/how_do_i_check_a_relay.htm The clutch coil, or it's wiring is more likley the cause, a bad transducer tells The PCM the pressure is low or high and wont let the compressor run, in fact Chrysler has a Technical bulletin about their transducers being faulty from 93-95 models, and here's a picture of the replacement part.


https://www.2carpros.com/forum/automotive_pictures/62217_9395_ac_transducer_1.jpg


You can bypass the tranducer with a piece of wire, this will eliminate it as the source, but not the harness, DO NOT run A/c like this, damage to the compressor WILL occur! At idle and during recharging, until it's full enough to keep the compressor running(enough freon), then plug it back in, it's a safety switch.
I will email the TSB about this.
Check the wires to the compressor with an ohm meter, the colored wire should be the power... put red lead on it, ground the other lead, reading should be OL, if it shows a low resistance reading, it's shorted to ground.
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Friday, May 14th, 2010 AT 6:23 PM
Tiny
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According to the schematic"”IF it was the A/C clutch coil the fuse should blow going to the A/C ---right but it doesn't? So, what I was referring to is the actually A/C relay coil side possibly grounding out where it goes to the PCM---not the relay contactor where the clutch coil current travels through it.

See Schematic below:

Intermittent troubleshooting problems like this can rack one's mind----But once again why would the PCM fuse blow and not the A/C relay fuse blow? The 10 amp fuse numbered 20 on the schematic above never blows. When the A/C cooling mode is in ON the PCM fuse will not blow right away but only after traveling for 20 miles or more and sometimes longer.

Is it possible the transducer has an intermitten short causing the PCM fuse to blow? Theory is 5 volts out but it could cause a short--thus --perhaps blowing the PCM fuse?

Incidentally, I do have access to All Data but I didn't know how to enlarge that schematic enclosed herin.

Thank You Very Much!


https://www.2carpros.com/forum/automotive_pictures/526262_57445920_1.jpg

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Saturday, May 15th, 2010 AT 6:55 AM
Tiny
MERLIN2021
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18 - 10 Amp
Engine Controller, Fuel Pump Relay, ASD Relay.
This the fuse blowing? I would start by checking grounds, This is a major cause of problems like this.
If you can scan for B and U codes, these require a good scanner, Most shops can read these, but the scanners sold at Autozone and stores like it do not. And try the self test, turn the key from off to on three times then leave it on on the fourth time. Count the flashes of the MIL(service engine light).
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-1
Saturday, May 15th, 2010 AT 8:02 PM
Tiny
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There are no codes other than 12 & 55 which of course denotes end of test codes from dash "ring out"procedures.

However early this morning I was traveling to get my youngest son when I encountered a CODE 43--ENGINE DIED----CHECKED OUT ALL FUSE---NONE BLOWN. It appears the IGNITION coil pack may have been the culpruit and not the A/C circuit I previously thought but I never got a code 43 before when it blew the PCM fuse!

I will check out for bad gnds as far as a scanner --the connector (DBL) LINK under the dash will not function even with a "good Shop scanner".

Thank You!
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Sunday, May 16th, 2010 AT 5:26 AM
Tiny
MERLIN2021
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https://www.2carpros.com/forum/automotive_pictures/62217_n_3.jpg


If your connector looks like this, check the grounds, pins 4 & 5 and power pin 16
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Wednesday, May 19th, 2010 AT 5:53 PM
Tiny
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Merlin2021,

Thanks every so much for your help---I discovered a frayed ground wire going to the distributor/coil assembly---repaired that then got a code 43---replaced coil/distributor pack---repaired that. Replaced spark plugs----I ran this vehicle for about an hour with A/C on high (cold air) ambient temp 92 F. Outside.

OBD1 system on this car. OBD2 1996 and up.

NO PROBLEMS! It had to be that poor ground going to the ignition pack causing the PCM to draw excessive amperage plus a coil/iignition pack going bad!

YOUR ARE A GOOD TECHTHANK YOU!

I LIKE THAT Moniker----MERLIN2021----ITS MAGIC!
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Monday, May 24th, 2010 AT 11:23 AM
Tiny
MERLIN2021
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Believe it or not, Fords and some GM's had OBD II in 95. Mainly Ford guy. Good work.
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Tuesday, May 25th, 2010 AT 2:36 AM

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