???? help
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From: Grand Bay, Al
???? help
Posting for a friend. He has a 04 ranger. 4cyl 5spd. Last week everything happened at 1 time. He said the cel came on, the a/c quit working and the battery died. He bought a battery. Had the codes checked. It was a cyl head temp sensor. He changed it to find the valve cover gasket needed to be changed so we changed it too. He still has no a/c. I'm gonna look at it in a little while. What should I look for first??
Cargo Master
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Sounds a bit fishy to me. The AC and the charging circuit and the head temp sensor are all controlled by the ecu. I would start by checking all the fuses and then the relays. I would definitely check all the grounds. Get a good wiring diagram, a meter, and a test light and start checking circuits. You can jump the air conditioner relay to see if the compressor will engage. If it does then it is a control circuit issue. And how did you change the head temp sensor without pulling the tranny. On my 03 it is on the back of the head next to the firewall. And if you changed the valve cover gasket then you had a lot of parts off (intake plenum) make sure you didn't miss hooking something back up.
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From: Grand Bay, Al
On his 04 its on top of the head between #2 and #3 plugs. That's how he new the valve cover was leaking. There was oil on top of both plugs and around the sensor. He said he checked all the fuses and they were good. I tried jumping the high and low press switches on the a/c and nothing.....
Cargo Master
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Go to the ac relay and try the jump there. If it comes on then you need to see if you have power to the coil side of the relay if so then it is back to the switch which tells the ecu to ground the relay circuit to engage the compressor.
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From: Grand Bay, Al
I put pwr to the clutch and the compressor kicked on. Works good. I started checking grounds. The cheesy factory clamp on the batt was broke. Changed it out then the truck didn't want to start. It took a few trys to get it started. When it did it smells like it was flooding. I could smell gas pretty strong. It is ideling around 1200 I reved it up to 3k and let off. It came down to about 2100 and stayed there for a few seconds then dropped to 12. Is a sign of the ecu going out?
Cargo Master
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A bad ground and a battery that went bad suddenly could cause ECU failure. Over the years I have seen a few ecu fail but it is some what rare. If they do fail it is usually caused by some event like a sudden battery failure of loss of ground. A loss of ground while in operation will send current to some places it shouldn't go. That being said you still need to check all your connections because you did have the manifold off and a lot of things where disconnected. High idle can be caused by idle air valve problem or a vacuum leak. I would also check and ensure the harness to the ecu is plugged in correctly
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From: Grand Bay, Al
While I was working on the truck and checking grounds. The neg batt clamp was real loose and it was broke in half. So basicaly it was just hanging on the batt. And it was corroded heavily.
So the damage could have been done there? I had a scanner hooked up and it was saying the coolant temp was -40f. It was about 95f yesterday so -40f isn't possible
So the damage could have been done there? I had a scanner hooked up and it was saying the coolant temp was -40f. It was about 95f yesterday so -40f isn't possible
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Post Fiend
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From: Connecticut
Not sure about the other issues, but a -40F reading indicates there is an open in the coolant temp sensor (ECT) circuit somewhere.
Post Fiend
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From: Connecticut
It could be that the 2.3L engine control system doesn't even use an ECT, and instead gets engine temperature feedback from the Cylinder Head Temperature (CHT) sensor...? I don't know a heck of a lot about the 2.3L so maybe someone who does can confirm/refute this.
So maybe your scanner is looking for ECT sensor feedback, and seeing none, concludes that there is an open in the circuit, and hence gives off a reading of -40F.
In any case, I noticed in the OP that the CHT sensor was already implicated as being problematic at some point, and so I would be focusing my attention there.
Post Fiend
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From: Connecticut
OK, then we have to assume the sensor is good and something else in the circuit is/was bad. I can see why you are suspicious of the ECU.
FWIW: According to the '02 wiring diagram for the 2.3L, the CHT circuit originates (VREF) at pin #66 of the ECU and travels to the sensor vis a vis a Y/LG wire. The other wire (GY/RD) is a common SIG RET back to the ECM (pin #99) shared with other sensors.
If the '04 is wired similarly, maybe you can do some more testing (continuity, shorts).
FWIW: According to the '02 wiring diagram for the 2.3L, the CHT circuit originates (VREF) at pin #66 of the ECU and travels to the sensor vis a vis a Y/LG wire. The other wire (GY/RD) is a common SIG RET back to the ECM (pin #99) shared with other sensors.
If the '04 is wired similarly, maybe you can do some more testing (continuity, shorts).