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Dodgerench
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3401
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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2003 Dodge Caravan: a 3.3 liter..Temperature..Engine Coolant..Volt

This answer was rated:

*I have a 3.3 liter, 2003 Dodge Caravan.
*My autoxray says the Code 118 Temperature Engine Coolant Volt is high.
*I changed the Temperature Sensor in the Thermostat housing.
*Code 118 still identified and engine light came on.
*Took it to Chrysler today, they got Code 118 and told me it must be in the wiring harness.
*They said they'd have to "wire around it". That is by-pass the harness and run wires from the "Sensor" over to the Computer.
*Could someone guide me what wires to run from the Sensor (there are only two on the connector for the "Sensor") and wire to the which wire(s) on the computer.
*I'm a mechanic and am able to do this fairly easily if guided.
*Thanks, J
HiCustomer welcome to Just Answer!.

I'd probably do the same thing if the cause of the open circuit couldn't be found nearby.

P0118 is set when your ECT voltage is unchanged from when it leaves the PCM at about 5.0 volts. This open circuit can happen anywhere between the PCM and its ultimate ground source, which is the sensor ground circuit.

graphic

Note that sensor ground serves every other sensor under the hood as well, so chances are good that if you have but one code being set, the K900 (dark blue/ dark green) circuit is OK to within a short distance of the ECT sensor. Check for continuity to ground on the K900 circuit to see if this portion of your circuit is OK. If so, it's one less wire you have to run.

The K2 (violet/ orange) wire is the sense circuit to the ECT and should show something very near 5v when unplugged if intact. If not, the circuit takes its feed from Pin 26 of the C1 connector at your PCM, which will be numbered on the open (terminal) face of the connector. There are only two connectors for the SBEC3 PCM and they smartly number them 1-40 and 41-80 to avoid confusion.

If you decide the sensor ground is missing, it would be handiest to splice into a K900 circuit nearby... like the intake air temp sensor in the air cleaner duct or even the cam sensor.

I think you'll be good to go now, but if you have any questions or problems, don't hesitate to write back. I'll be glad to help.

Thanks,
Ed
Dodgerench and other Dodge Specialists are ready to help you
Customer: replied 7 years ago.

I am capable of doing about everything....but on older models. The answer above is for mechanics with testing equipment and more knowledge than I have. Is it possible that you can give me a simpler wiring discription.....

 

ie: take a red wire and wrap it to the ____wire on the the sensor connector, and a blue wire and wrap it to the ____ wire on the sensor.......then run the red wire to the ____wire on the computer, and the blue wire to the ____wire on the computer.

 

I'm shade tree for most. I appoligize for such an agrarian request.

Thanks, J

No worries. It would be very helpful if you could locate a digital voltmeter though... the chances of both circuits being cut are practically zero, so it would save you considerable work. Is there a chance you could locate one?

Digital meters have become very reasonable in price and can be found at a number of places like auto parts stores, Big Box hardware stores and Sears for $20 or less... with a $4 model available at Harbor Frieght that works just fine. I'd be happy to guide you through the process and I'm sure it would make things easier on you as well.

Hey, before we get too far into this... check the wire colors on your ECT sensor to see if they match the connector wiring on the sensor you replaced. That's just in case we might be working on the wrong sensor (which happens).

Talk shortly,
Ed
Customer: replied 7 years ago.

For three days when my wife starts the van, it bucks and maybe dies, then try again until it runs. today when we took it to chrysler, it started perfect, started perfect again when we picked it up, and started and ran perfect thereafter. Felt like a fool, cause it wouldn't do what all it does off and on. The engine light didn't come back on today either.

my son has a volt meter. so what do I set it on, and where do I use it (ie: at the connector, etc.) This all is worth a lot to us. Chrysler wants 210 dollars to by-pass the wiring harness. If I can do it, it'd save a bunch.

Thanks, J

Customer: replied 7 years ago.

For three days when my wife starts the van, it bucks and maybe dies, then try again until it runs. today when we took it to chrysler, it started perfect, started perfect again when we picked it up, and started and ran perfect thereafter. Felt like a fool, cause it wouldn't do what all it does off and on. The engine light didn't come back on today either.

my son has a volt meter. so what do I set it on, and where do I use it (ie: at the connector, etc.) This all is worth a lot to us. Chrysler wants 210 dollars to by-pass the wiring harness. If I can do it, it'd save a bunch.

Thanks, J

Dang, I really hate intermittent problems too! They have a way of making everyone look stupid... =/

Set your meter to 20v DC. To test the sensor signal circuit, disconnect the sensor... turn the key ON... then touch the red test lead to the terminal for the violet/ orange wire. Expect to see 5.0 volts if the circuit is good, probably zero volts if not.

Set the meter to 200 ohms for the sensor ground circuit. Touch either test lead to the dark blue/ dark green wire and the other to a good ground source or to battery negative. A good circuit will show 20 ohms of resistance or less since lower ohm readings indicate better circuit integrity.

Familiarize yourself with what an open circuit looks like on the meter (probably OL) and then touch the test leads together to see what a perfect, complete circuit looks like on this meter. It usually shows SOME resistance... maybe an ohm... but that's OK. We're just doing continuity checks right now, just to see if the circuit is connected to something or not.

Once we find out which circuit is bad (IF it'll act up)... the re-wire will be pretty easy. I sure hope you can catch it in the act of screwing up because it's probably gonna test OK unless the CHECK ENGINE lamp is coming on at the time.

One trick I use for finding a broken wire in the engine loom is to give it a decent tug at one end to see if it pulls out of the harness. If it's in good shape it won't break but if it does break, you've now got a yardstick with the broken wire to lay next to the loom to locate the spot of the bad spot. Just imagine what it would take to actually break a healthy 18 gauge wire and stay short of that feat!

Talk in a bit, J!
Ed
Customer: replied 7 years ago.

My son came in just now and said he'll try to carry out what you've suggested.

Could you tell us what the re-wire will be for each...so that we can complete the re-wire once he finds which circuit it is

 

We'd certainly appreciate it. We'll "Accept" your advise now and get off the computer so that we can do as you have suggested.

 

Please tell us the re-wire for each before I shut off the computer, so that we may go to work. What wire to go to where.

Thanks again, J

You bet. Let's start with the ECT location... just to be sure you've got the right one.

graphic

We good? I actually imagined it on the other end of the engine, so it's a good thing I checked it out. You won't have many good sources for the sensor ground circuit nearby, but the MAP sensor would be one choice. The MAP is located on the top of your intake manifold upper plenum and is the only 3 wire sensor in the area. This picture shows the engine with the plenum removed.

Repair involves splicing a wire to the sensor ground circuit (dark blue/ dark green) from any other source you find or you can go all the way to the PCM. I say splice because the wire just needs to tap into the circuit.

The power feed to the sensor (sense circuit, violet/ orange) can be taken near the PCM and run directly to the sensor connector, cutting all the old wire out in between.

Your PCM is located just forward of the battery and has two 40-way connectors. Print the wiring diagram if possible I sent earlier for reference while you're out at the van... it's handier that way.

Locate Pin 26 on the open (terminal) side of the connector and then find the violet/ orange wire on the back side. Cut it so that you have a good working length and connect tis wire to the same colored wire at the ECT connector.

If you choose to go to the PCM for the sensor ground circuit, you'll find it on the other 40-way connector at Pin location 43. THIS wire must be left intact to service the rest of the engine, but you can strip a small section of insulation off to solder a wire to it for this purpose. Run that wire to the same dark blue/ dark green location at the ECT connector, where you can cut the wire there to join with this jumper you've built.

I'd sure give these two wires a good tug even if you don't have a meter handy, J. It's a short path from there to the PCM and there really isn't much that can happen so I believe you'd find it pretty easy.

Good luck,
Ed
Customer: replied 7 years ago.

THANK YOU ED!

We're going to work on it now.

Thanks for your EXCELLANT help, J

 

p.s. yes, that's where my ECT is located

Wonderful! Keep me on the speed dial!

Ed