OP
Did I loose you Jerry?Just don't try to convince me the vented hood was the cure since Jeeps don't need that to run well in even very hot weather.
‘98 TJ goes into safe mode when ambient heat is 85+ degrees
- Thread starter Stump Jumper
- Start date
Insulating things might help, but I would also recommend testing fuel pressure. The regulator & filter is part of the fuel pump module. Did you drop the tank to replace that?
On your 2.5l, there is a fuel pressure test port on the rail. The test procedure is found in the FSM, which you can download here.
Which sensors did you change and what codes did it throw? Hold on to your old sensors until you figure this out, because Mopar sensors are typically best and some are NLA.
OP
RMETeejay, thanks for responding. I did drop the tank and replaced the entire fuel pump just days ago. It’s the second one I have replaced in three years. The symptoms were hard to start, prime with the key several times and then it would start. That is fixed now since I replaced the fuel pump.
Now my only code is the P0505, and I checked the IAC wire harness back to the PCM for continuity which was all good. I don’t think I’m getting any power to IAC from the PCM. The IAC is a brand new MOPAR part so I don’t think it is a bad part.
Is there a way to check for a reference voltage on the wires for the IAC Valve?
I did take the IAC Valve out, left it wired up and started the motor to see if the valve motor moved, it did not.
Again, thanks for your help
If the continuity to the PCM is good, check the IAC for power and ground. There should be no resistance between the ground wire on the IAC and a nearby ground point and you should see voltage on the other wire.
OP
JB, I don’t see any voltage on any of the four wire harness at the IACV. Is there a procedure that I might need to follow? I started the motor and checked each line with a ground. ?
OP
I have good continuity PCM to the IACV but I don’t know which of the wires are ground and which ones are voltage. I read that the PCM reverses polarity on the wires to drive the motor on the IACV, but I don’t see voltage on any of the wires. The four wires are colored grey/red, yellow/white, brown/white, purple/black.
Download the FSM at the link I shared earlier. Under the wiring diagrams (page 8W - 30 - 13), it shows the wiring going directly to the PCM. That tells me that it is grounded through the PCM (maybe the wires with black?).
If you can peel back the rubber boot on the C2 (probably middle) PCM connector, you could attach your multimeter to each wire in order to verify continuity and ground. PCM grounds shown on page 8W - 15 - 4.
OP
I see -9.3vdc on two of the leads when connected to the VT/BK as a ground directly out of the PCM connector.
OP
I can see a sticker on your PCM with 'security' on it. Do you know if it's a replacement? My 04 with 4.0l does not have that, so just curious. Can you verify that you have the correct PCM? 2.5l engine = EP0
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Thanks for catching that, yes, during the last three years of trying to get it running properly I replaced the PCM with one that is matched to my VIN. Not sure how to tell if it is EPO? I still have the old one and no, it didn’t make a difference in anything while I worked on fixing it. However, I am down to only one code, that being the P0505, IACV issue. The TJ starts and seems to run fine but I know the IACV is not operating because I have two MOPAR IACVs and the piston is not moving on either one of them. I know because one is extended and the other is retracted. When installed, the extended one causes a very low idle and the retracted one causes it to idle very high.
OP
It sounds like your PCM is the correct part number. Since other sensors aren't malfunctioning, it's likely not causing the issue.
The FSM says the IAC can only be tested with a special tool (DRB scan tool). Since it's new, it's unlikely that it's bad.
Since your issue is ambient temperature dependent, I'd suggest testing the intake manifold air temperature sensor.
The FSM says the IAC can only be tested with a special tool (DRB scan tool). Since it's new, it's unlikely that it's bad.
Since your issue is ambient temperature dependent, I'd suggest testing the intake manifold air temperature sensor.
- In the FSM, there is a procedure to measure the resistance of the sensor and a corresponding temperature chart (page 14 - 42).
- Measure the resistance with the ambient temperature below where you see the issue, and then also above that temperature.
- In addition to measuring directly on the sensor's terminals, I recommend also measuring at the PCM. This would allow you to see if the wiring between the sensors and the PCM are also good.