Evap and ses light question 95 Z28
 

Deleted my Evap before i found out it causes a ses light. So now i need to have that code eliminated because its causing my fans to run all the time which keeps my car running very cold! Its winter here and in the low 30's high 20's as is.

After searching my ass off i found a hint from injurer that a resistor could be used? From 100-2000 ohms? I need to know what ohm to use and could i buy it at radio shack?

Also does having a ses code change how the car uses gas? and does having a ses light have any negative effects on performance?

Re: Evap and ses light question 95 Z28
 

Assuming you're talking about DTC 26, if the code is set the PCM will illuminate the SES light and disable the driver for the EVAP solenoid - this won't cause any performance issues whatsoever.

Not sure on the resistor you need though...

Re: Evap and ses light question 95 Z28
 

Measure the resistance of the stock solenoid. I think its pretty low, about 15ohms, to produce a ~1 amp current load when it operates. But the exact resistance isn't important. The 2,000ohm resistor works fine for the skip shift solenoid delete, it will probably be OK for the EVAP solenoid.

Re: Evap and ses light question 95 Z28
 

To build on Fred's post....

Measure the resistance of the stock EVAP coil. That will give you the resistance value you need(pay attention to the meter....does it state ohms or kohms...if kohms, then multiply reading by 1000 to get ohms).

Take that value(in Ohms) and divide it by 13V. This will give you the current(roughly) that the coil will pull. Then, take the current value and multiply it by 13V. This will give you the wattage of the resistor that you need. If you don't get the correct wattage resistor, it will smoke it.

V = volts
I = current
R = resistance
P = watts

So...if you measure 15 ohms....then do this....

I = 13V/15
I = 0.866A

So, the current it will pull is 0.866 Amps.

Then....

P = V x I
P = 13V x 0.866A
P = 11.258W

You will need a resistor with a rating of over 11 watts....you are stepping in to wire wound resistors at that current.

Let me go measure my EVAP solenoid for resistance real quick(I hope it's higher than 15 ohms). I'll do the math for you.

Re: Evap and ses light question 95 Z28
 

It measured 24.5 ohms.

V = volts
I = current
R = resistance
P = watts

So...if you measure 24.5 ohms....then do this....

I = 13V/24.5
I = 0.531A

So, the current it will pull is 0.531 Amps.

Then....

P = V x I
P = 13V x 0.531A
P = 6.903W

That's better on the wattage side(the higher resistance means a lower current pull, thus a lower wattage). A 10 watt; wire wound resistor @ 25ohms should do it. That will simulate the EVAP solenoid to the letter. However, if the PCM is looking at just some type of voltage drop....then you might be okay with a higher resistance.

If you were to use the 2000 ohm resistor.....

I = 13V/2000
I = 0.0065A

So, the current it will pull is 0.0065 Amps.

Then....

P = V x I
P = 13V x 0.0065A
P = 0.0845W

A 1/4 watt resistor @ 2000 ohms(2200 (I think) is a standard value easy to find) would work for this case.

Re: Evap and ses light question 95 Z28
 

I measured mine and here is what i got.
http://i694.photobucket.com/albums/v...a/SAM_0434.jpg


Ok so

13v/25= .52A

13V x .52A =6.76W?

So a 10 watt resistor at 25ohms would be what i need? Any idea where i would find one of these?

Re: Evap and ses light question 95 Z28
 

You do not need to match the resistance of the solenoid. I probably shouldn't even have mentioned checking the resistance. The PCM is just looking at whether the circuit is open or closed. If there is nothing plugged into the harness connector, the PCM will see infinite resistance when it commands the solenoid to open, and trip the trouble code. The resistor prevents the PCM from seeing infinite resistance when it commands the solenoid to open. A 2,000ohm resistor is a convenient selection. As Eric is pointing out, matching the solenoid resistance results in a higher than necessary amp load, and requires a higher wattage rating on the resistor.

Re: Evap and ses light question 95 Z28
 

So is what your saying is the computer is looking for anything other than infinite resistance? I will go ahead and get a 2,000ohm 1/4 watt resistor and a 25ohm 10 watt resistor. I will use the 2,000 one first.

One last question in a 95 what was the color of the two wires the connected to the plug for the Evap solinoid?

Re: Evap and ses light question 95 Z28
 

Brown wire going to the solenoid was connected to 12 volts and the green/white wire was connected to the PCM.

The PCM looks for voltage on the green/white line. It's not looking for resistance or the lack there of.

You don't need a 10 watt resistor. As was recommended earlier. If you use a high enough resistance to tie the 12 volts to pin 10 of the Blue PCM connector, you need not worry about the wattage.

If the connector is still there, just shove one end into each of the pins and wrap it. Done.

Re: Evap and ses light question 95 Z28
 

Im confused shove one end of what? and into which connector the pcm? or the plug for the evap solinoid?

Am i supposed to put the resistor in somewhere else because i thought i needed to connect it to the two wires that went to the evap solinoid.

Re: Evap and ses light question 95 Z28
 

Your local Radio Shack should have both components in stock.

Re: Evap and ses light question 95 Z28
 

Put the resistor in the end of the evap connector(should be no need to cut the connector off). You thought correct. When you put the resistor in the connector, if it's loose, just fold the resistor leads to double up the thickness.

Re: Evap and ses light question 95 Z28
 

Ok so radio shack only carries the 2200ohm in 1/4 watt and i tried that with no luck! Maybe i should disconnect the battery for a minute?

Re: Evap and ses light question 95 Z28
 

Ok resetting the batt had no effect but it seems like the light takes a couple seconds longer to turn on now. should i try a different resistor?

Re: Evap and ses light question 95 Z28
 

Take the coil itself and put it back on(just connect it to the harness)....see if it goes away. If it does, then the higher wattage/lower ohm resistor(25ohm/10watt) maybe in order. If it does not, then a code could also be getting set from the evap purge switch too. That switch changes state when the coil turns on to verify that the purge is actually taking place.

It would help to know all the codes the car is throwing.

I don't know if the '95's had them(evap purge switch). Are you in Cali or Canada?

You may have to have the EVAP codes programmed out.