Transmission Temperature

[Matt400]

Here is what I did:

 

[bill8333]

Can you tell me what size the cooler lines are on a 2004 TD with a 48re trans.



Thanks Bill

 

[EFretwell]

Do you know if the 03 have the same fan setup as a 98. 5?

 

[Matt400]

Do you know if the 03 have the same fan setup as a 98. 5?

They do not.

 

[MMeier]

Matt, I'm going to attempt this tomorrow morning, if I can get to the electronics store and get the 180 ohm resistor. Do you foresee any problem using a switch with a lighted paddle so I know which way is on? I went and wired in a toggle today to control my A/C pump and I guess the fan circuit does not "always" see high pressure in the system and i had some blow off through the relief valve on the compressor, didn't seem like the fan was engaging fuly like it was this afternoon in 105* heat. Do you see any problems using these together? Thanks,Mark

 

[Matt400]

Do you foresee any problem using a switch with a lighted paddle so I know which way is on?

No but you won't be able to use the circuit you are switching for the toggle power if that is the way the switch works. The circuit you are toggling is simply a variable resistance to ground.

I went and wired in a toggle today to control my A/C pump Do you see any problems using these together?

Dunno about that, why the toggle for the pump?

 

[MMeier]

Dunno about that, why the toggle for the pump?

Because I have been getting P Code 0647, something about A/C clutch relay circuit voltage high. Went through the flow charts and everything, but could not find the problem that way, think it is probably just the computer, my old '94 I had to do up this way, it worked great while I owned it.

 

[Matt400]

Thats and odd one, have you tried replacing the the A/C clutch relay?

It seems like the weak link in that circuit that could cause your trouble.



For example. . A/C has been on and when you switch it off you have commanded the ECM to turn it off so the ECM turns it off but the contacts stick in the relay leaving it energized. The ECM would see that and log a P0647.



If that were the case then you may not be hitting the toggle fast enough when you turn the oem dash switch off or you may not have the toggle wired in such a way that stuck contacts in the relay are still being seen by the ECM.

Thats me just thinking in theory about a possibility.

 

[MMeier]

Yep, swapped with other relays and no change. On your MFO mod, just went to Radio Shack, closest resistor I could find was a 220 ohm, . 5 watt. Will one of those work? Does the watt rating matter along with the tolerance of the resistor, want to know before I go out there in this wonderful heat and start splicing and soldering. Thanks!

 

[MMeier]

That Pcode (0647) has been going on all season so far, I just put he switch in yesterday, ran off my aux fuse block through a toggle switch and cut into the wire by compressor, stock original wire is loose down there now.

 

[Matt400]

That Pcode (0647) has been going on all season so far, I just put he switch in yesterday, ran off my aux fuse block through a toggle switch and cut into the wire by compressor, stock original wire is loose down there now.

What you explain here sounds like an "added" 12v supply for the clutch, I don't see how that could work. I thought you were going for an added "cut out" for that circuit?



I wouldn't use the 220 resistor, I worked on all the combinations for a while settling with the 180 on an 03 model as it fooled the ECM to think coolant temp was at 220 degrees and worked well, I confirmed the 220 with a scanner. . 5 watt should be fine.

 

[MMeier]

I wouldn't call it an "added" 12v, seeing as how the only way the compressor gets its voltage now is when I throw the switch, I "disconnected" the original wire in the stock loom... . i. e. , cut it. Make sense yet? I guees I'm off to the electronics store downtown and hope they have a 180 ohm resistor.

 

[Matt400]

There must be a better way to fix the P0647 code. Having it wired that way will also bypass other needed commands such as the fan clutch duty cycle.

I have a 2 page troubleshoot chart on that code I could fax you if you pm me a fax #.

 

[MMeier]

On the MFO, in override, only pins 2 and 3 are connected, not 1,2 and 3, correct? That way, the temp gauge "reads" correct under normal operation, and around 220 or so while in the override position?

 

[Matt400]

1 & 2 or 1 & 3 depending on switch position, the switch needs to cut out the oem sensor and substitute the 180 ohm resistance. Fax coming shortly.

 

[MMeier]

Got it!! Thanks, I'll keep posting here whats what with the POS!!! Thing is really trying my patience as of late!! And not just the A/C, and fan issues either!!

 

[Matt400]

On the MFO, in override, only pins 2 and 3 are connected, not 1,2 and 3, correct? That way, the temp gauge "reads" correct under normal operation, and around 220 or so while in the override position?

I just re read this. .

In override the temp gauge on the dash will be driven to 220, this happens because the ECM sees a value equal to 220 from the 180 ohm resistor and then commands the temp gauge to 220. Also you will note in override the oil pressure gauge will drop, that is because since the ECM sees a higher coolant temp it thinks the oil must then be thinner so commands a lower reading on the gauge.



The fan clutch will not just "snap on" when you hit the toggle, it will engauge smoothly but slowly as the 220 value is analyzed.



In normal mode the the toggle should just connect the temp gauge circuit and cut out the resistor you have installed to a good ground.

 

[MMeier]

OK, got it hooked up with the 180 ohm resistor, when I go from normal to over ride the engine speed goes up to 1000 RPM 's for a few seconds, then goes back to its 775. It does not however go to 1000 RPM after 8 minutes (or 15 for that matter). Also, in override the temp gauge goes directly to the red line on the high end of the scale and trips the check gages lite, sound right, or do I need a higher (numerivcal value) resistor in there?Also... . when I drive off with it in override, it seems to take till about 1600 RPM before I hear the fan, does not seem like it comes in at idle, is that because the temp gauge is almost pegged?

 

[Matt400]

Did you cut only the tan wire/black stripe at the coolant temperature sensor?

 

[MMeier]

Did you cut only the tan wire at the coolant temperature sensor?

Yes I did, had to to split it for the switch, correct? Ran 2 coductor wire from there to my switch then a seperate ground wire with the resistor in it. Left the red one alone.