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Joined: Aug 2002
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New CEG\'er
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OP
New CEG\'er
Joined: Aug 2002
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Patient is '98 SVT E0 w/ 140,000 miles. Been great car but nothing lasts forever.
Died at 60mph during long highway trip. Cranks but won't fire. CEL is lit both with switch on and when cranking. No pump noise, no pressure behind releif valve. Fuses and relays OK, gets power to harnesss at pump, so, new fuel pump.
Wrong. "Power" was only 6 volts. Jumper across relay does kick pump into action. Should have tried that first. Well, pump replacement would have been needed soon anyway. Onwards.
Relay not getting low side signal. Got code reader and it cannot communicate with PCM. Harnesses and grounds seem to be OK but I'll be looking closer.
Anything else to check before replacing PCM?
silver '98 E0
bone stock except
225/60 -16's on 16 x 7's (45 et)
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Joined: Aug 2002
Posts: 13
New CEG\'er
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OP
New CEG\'er
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Attempted to scan for codes a dozen times. Key is on at the appropriate time. Both my laptop setup as well as the rented scanner come up empty.
Symptoms (no fuel, no spark, no PCM diagnostis) seem similar to what others have seen with short and blown fuse #4 on PCM power. My fuse is good. Grounds at battery terminal plate are clean. Could this be a break in a ground wire?
Leads to TPS, crank and cam sensors look good. Are there voltage or continuity checks to make before swapping these out?
Even if all these sensors were bad wouldn't I still get codes?
Thanks for the guidance.
silver '98 E0
bone stock except
225/60 -16's on 16 x 7's (45 et)
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Joined: Sep 2002
Posts: 1,788
Hard-core CEG\'er
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Hard-core CEG\'er
Joined: Sep 2002
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Several things to check:
The DLC (Data Link Connctor) has to supply battery voltage on pin 16 (Key On) to the scan tool and grounds on pins 4 & 5 of the DLC. Check these first. Loss of power will cause a "no communication" message on most scanners. Pin 16 is supplied by either Fuse F24 or F28 in the underdash fusebox depending on date of manuafacture. On laeter productions, F24 also supplies power to brake light switch for the stop lamps. On early production, F28 supplies pin 16 and the power seat module, if present.
Assuming a return style fuel system, the fuel pump is supplied by the fuel pump relay in the underhood fuse box. High side coil power is supplied via the NO contacts of the PCM POWER relay. Low side is controlled by the PCM and may be jumpered to ground to test relay and pump power function when the PCM RELAY is energized.
Check IGN ground to battery ground at the TPS. Check Vref at the TPS.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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Joined: Nov 2003
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Hard-core CEG\'er
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Originally posted by Ex-Mean'Tour:
If you end up needing a PCM let me know as I have a new remanufactured one I got stuck with from the Ford dealer. Installed once for a few minutes is all. I'm not sure if it would work for you, but it might. A Dealer could let you know. It's part number # WU72 12A650 SB
That won't work for him. A 98 E0 SVT has a ECU code of RJL1, and since yours was not for a SVT, it won't run correctly.
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Joined: Jan 2005
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Hard-core CEG\'er
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Hard-core CEG\'er
Joined: Jan 2005
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Originally posted by CSVT1214:
Originally posted by Ex-Mean'Tour:
If you end up needing a PCM let me know as I have a new remanufactured one I got stuck with from the Ford dealer. Installed once for a few minutes is all. I'm not sure if it would work for you, but it might. A Dealer could let you know. It's part number # WU72 12A650 SB
That won't work for him. A 98 E0 SVT has a ECU code of RJL1, and since yours was not for a SVT, it won't run correctly.
Shhhh, don't tell him. I need to get rid of this POS I'm tired of seeing it.
MUST SELL - ECM computer new for a 98 V6 mtx + pats
Now trolling in a Red Nissan 4 x 4
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Joined: Aug 2002
Posts: 13
New CEG\'er
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OP
New CEG\'er
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Tony,
Further harness checks have revealed PCM harness worn through sheath and insulation on two wires. This happened where the harness squeezes between engine lift hook and A/C tube. When she went down it was a hot day, A/C full on, heavy condensation, wet and bare aluminum on copper. Bad combination.
The A/C tube does not test out to be grounded so these two wires only shorted to each other. Players are:
Pin 90, 7-PC28 (Yellow)
feeds TPS, fuel tank press. transducer, exhaust pressure transducer (didn't know we had that)
Pin 97, 95-OC28A (green/yellow) seems to be one of several parallel feeds to PCM relay. Can't quite decipher what it does.
Would the combination of these two cause PCM failure?
After a good clean and re-wrap we'll see if this is the problem or just an incidental find along the way.
silver '98 E0
bone stock except
225/60 -16's on 16 x 7's (45 et)
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Joined: Jun 2005
Posts: 5,345
Addicted CEG\'er
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Addicted CEG\'er
Joined: Jun 2005
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"Would the combination of these two cause PCM failure?"
Yes, wiring harness shorting out has been known to do that.....
... but I would check fuses and relays first.
In addition, according to Chilton...
...the 1998, 1999 SVT Pin 90 goes to reference voltage and is <0.050 V at hot idle.
and Pin 97 is Vehicle Power and at hot idle is 12 to 14 V.
Now would be an excellent time for F111D F to chime in with his technical assessment.
Yes, let's try these first, you can't lose at this point. If it doesn't work, then you can consider a new PCM.
Edit. TPS Signal is Pin 89 and at hot idle should be 0.53 to 1.27 V.
Last edited by Tony2005; 08/05/06 01:04 AM.
"Always do the cheap and easy ones first."
1996 V6 ATX 96K miles
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. If you confirm those are not the problem, check Crankshaft Position sensor (CKP) and Camshaft Position sensor (CMP).