Ok all you electrical gurus, give me some ideas where to go. I'd installed a new CAGS unit a couple of weeks ago after getting the P0803 code fairly consistently. The auto tech guys checked the old unit and said the resistor had gone bad. All was well until today when once again the P0803 code popped up. I'm guessing that the resistor had gone out again. Does this mean I'm getting current spikes in this circuit? If so what could cause it? I should say that when this first happened I also had several other historical codes (U1096, U1064, U1016) but the skip shift code was the only current one. Thanks for any help you can give me.

 

I might suggest changing sources on the CAGS eliminator. If the one being used has a resistor with an insufficient power rating (watts) it's conceivable it could be frying it. Also make sure the pins are getting a good plug connection when you connect it up.
If those 1064, 1016 and 1096 codes are in the RFA section of your DIC, then you can just disregard them.
HTH

 

Current flow is the result of voltage and resistance in the circuit (i=v/r). Since Voltage should be constant, and resistance is constant, the current should be constant. So either the voltage on that circuit is spiking or your resistor rating is low and burning out.

I can't recall if the voltage on that circuit is +5V and controlled by the BCM or not, so it's possible that the voltage is somehow higher than allowed but you'd expect other problems as well. Get a different CAGS unit and see if that works, and measure the impedance before installing just for your records. It may help if it happens again.

 

I haven't looked at that circuit to verify activation voltage for the CAGS solenoid, but if I had to guess I would guess 12V since it is activating a solenoid. Not sure though.

katana ace: Let us know what happens if/when you get a chance to address this issue.

 

Just use the plug that you have and add the higher wattage resistor of the correct resistance, Then seal it up with High Temp RTV. You can get the resistor at Radioshack for about a buck.

BC

 

And if memory serves me correct it is 2.2 ohms.

 

Thanks everyone, I had our electronics tech (I work at a community college) solder in a new resistor and the RTV is setting up as I write. I'll prob. install on Sunday to allow the RTV a full day to set. Hope the 2.2K ohm value is correct as I got that # from a earlier post on the forum. I'll keep you all informed.

 

got it in, car operates normally,we'll see. interesting to note you can indeed install this component backwards (as I tried to do several times before getting it right). wonder if this can have a negative effect?

 

I decided to go with a 2.2k ohm 1/2w instead of 1/4 like I've seen used. So far so good.

 

Nope!! The compoet inside the CAGS Module/Plug is a resistor. There are no polarity sensitive resistors. If the wattage is wrong and the current is high, it will just smoke.

You know what resistors are made out of,,right??? Smoke! Cause when you let the smoke out, they dont work any more.

BC

 

So thaaaaat's the reason it's called a "smoke test" when you flip the switch!

A least that's what we called it in the Navy.

 

They still call it a smoke test!

We smoked a radio receiver 24 VDC power supply just yesterday. Wow,, did it ever STINK! When we replaced the card, the Radioman said "SMOKE TEST" just before he flipped the breaker on!

BC

 

The old selenium rectifiers had the most fragrant smell. Much akin to the smell of burning hair. Yacko!

 

All, our electronics tech just told me that he checked the original resistor and found that it was a 1/4 watt rating. So far the 1/2 watt replacement has been working just fine. Any of the electircal gurus do the math for the volt/amp draw on the skip shift selenoid to see if 1/4 watt is under rated for max potential power draw?

 

In a common DC circuit Power (watts) = I (current) x E (volts). I don't know the current draw of the solenoid nor the activation voltage (5V, 12V?).
Basically, as a rule of thumb, you can have a resistor that's too big with no ill effects; having one that is too small however usually causes it to burn out.
BTW, that solenoid presents an "inductive" load to the circuit when it "fires" and reacts differently than a "resistive" load and can have an affect on the proper design size of the resistor. Not trying to get too far into DC ciruit theory here.
Suffice to say: If the 1/2 watt works, fine. If not, a 1 watt would be next.

 

Absoulty!!! E= I X R and P= I X E

Formulas that I will always remember!

BC

 

I was planning on building my own but found that I couldn't get the right connectors to build my own so I got one. I made a post to find out about resistor size and was told that it was 2.2k.

I checked the one that I got and it was 15.1 ohms, so I checked the resistance across the solenoid and it was 13.6 ohms. I plan on putting in the one that I have and see how it does. I am however wondering where people are getting the 2.2kohm number?

If I were to assume a voltage of 14.5 which is what typical automotive components are designed to along with a 15.1 ohm resistor, then the current draw on this circuit would be 0.96 A and the resistor would need to be 13.9W (V=IR and P=IV). With a 2200 ohm resistor, the
current draw would be .00659A and the power drawn would be .095 W.

The schematic shown in the service manual doesn't show any other resistors so it would likely be possible to find the activation voltage by putting a multimeter across one of the tabs on the top side of a fuse and the other to chassis ground (hope that is clear).Hope the schematic below helps.

Now I am not an electrical engineer, but my friend is and he recommended that I use the 15 ohm resistor b/c by using the large resistor it would not clean the ignition relay properly and could result in reduced life, I plan on asking him a bit more about this tomorrow.

[IMG][/IMG]

 

well the 2.2k ohm .5 watt resistor appears to have solved the problem. car running fine, even intentionally let 1st to 4th shift light come on and hold for a while (thinking the curcuit was energized and current flowing thru resistor) with no ill effects. Small side note: when installing new higher wattage resistor I used generous amount of high temp rtv that encapsulated resistor as compared to original unit that had only a light surface coating of regular rtv on it. vibration protection and heat sink was the idea

 

 

I installed my 15 ohm one as well and haven't seen any problems either.

From what I would guess, as long as the PCM doesn't see 12V then it assumes that the solenoid is working and doesn't send a code, but obviously you don't want too small of a resistance or you would end up burning up the insulation on the wires.