VID: Advanced EFan Issue - anyone seen this before?

[Mr. P.]

I helped my best friend swap a 5.3L motor into his '02 S-10, the truck originally had a 4.3L V6 in it. We installed a PCM from a '99 5.3L Silverado and hooked-up pin 42 to the Efans; during testing, fans work great when you manually command them on, but when allowed to behave 'normally' Pin 42 only keeps the fan relays grounded for about a quarter second and cycles/pulses the fans - here's a video of the problem. (http://www.allensrodeophotos.com/Steve/S10Swap/PulsingFans.m4v)

We tried completely re-flashing the PCM, no change. We took the S-10 PCM and wrote the tune to it, no change. We are totally clueless what the issue is, or even how to go about debugging what is going on - how do you troubleshoot a problem like this???

FYI Pin 33 is totally dead, we are only driving the fans at full speed with Pin 42.

The swap went fine, we got the whole project done in a few days, plus a few more nights after work to resolve a few gremlins. Pic of the finished swap, we went for the OEM look:
http://www.allensrodeophotos.com/Steve/S10Swap/_DSC0686.jpg

Any insights into the efan problem would be appreciated - it's our last bug and we're all out of ideas to try.

Thanks -

Mr. P. :)

[ChipsByAl]

Nice job. You need to post your tun file so it can be checked by others for any problems.
Al

[joecar]

That was quick... it does look very OEM.

[CashDude]

Did you run both grounds to pin 42?

If you ran one to pin 33, you have to change the function of the pin from recirculation door to fan #2 on the 99-02 truck PCMs or you will get the relay clicking on and off really fast like that.

Also, pin 42 and 33 are on separate sides of the PCM.

[Mr. P.]

Did you run both grounds to pin 42?
No, I installed a diode between the green and blue trigger wires to make 'one-wire operation', if you ground the blue wire you get high fans, if you ground the green wire you get low fans; the diode makes it possible that you don't have to ground both for high fan operation. The blue (high) trigger wire has been pinned to pin-42, the green (low) trigger wire I ran through a 'reversing' relay that in-turn is activated by the A/C request signal. So, strategy here is when you turn the A/C on, you get low fans; when the ECT gets hot, the PCM turns on high fans. We have no problem with low-fans operation, and if we command high fans manually from the bi-directional interface they work fine, but if the PCM is left alone then it will cycle the fans instead of keeping the relays on when the ECT setpoint is exceeded. Very frustrating. :(


If you ran one to pin 33, you have to change the function of the pin from recirculation door to fan #2 on the 99-02 truck PCMs or you will get the relay clicking on and off really fast like that.
We ran nothing to Pin 33, it's dead - using a VOM I verified that it is not grounding under any condition. But I suspect that Pin 33 has something to do with the issue here, I am wanting to learn more as to exactly why.


Also, pin 42 and 33 are on separate sides of the PCM.
Way ahead of ya on that :thumb_yello:

Mr. P. :)

[Mr. P.]

That was quick... it does look very OEM.
Yeah on the S10 forums they're flat-out calling us liars if you can believe that crap - seems the most of those folks are taking 6-18 months to do their V8 swaps. Thanks for the kudos, we are very proud of it. My friend is driving it to/from work now, lemme tell you the first 2 gears are *completely* useless LOL when downshifting at 25-mph the S10 just murders the tires all the way through second hehehe fun, fun, fun... :rockon:

Mr. P. :)

[ScarabEpic22]

That swap looks really good man, guess if you know what you're doing it can be done quickly, too bad it'd probably take me at least a few months to get it done. Helps if you have all the parts though I assume haha.

Just curious, what OS are you running in that PCM?

[Mr. P.]

I put a full build thread on silveradoss.com - http://www.silveradoss.com/forums/index.php?showtopic=53984

We found the answer to the pulsing efan issue, we had the low and high ECT cut-in temps at different values - when we put the same numbers in for both the low and high cut-in values the fans quit pulsing (remember this is for the '99 Silverado PCM which only has pin 42 available to operate the fans).

Mr. P.