Problem Using Pin 30 For Electric Fan Control

[portmod7]

Ok, hopefully I'm putting this in the correct spot....

I have a MS-II v3.0 with v2.905 code.

I am attempting to use the FIDLE circuit to control the relays for my electric fans. I am using these ( http://www.waytekwire.com/item/75730/SO ... CRO-RELAY/). I am trying to ground the coil side of the relay with the ecu. What I'm running into is that I am getting continuity to ground when I should be, but it evidently is not allowing any current to flow because the relay is not closing and turning the fan on. I can run a jumper to ground the coil of the relay manually, and the fan kicks on like it should.

Any idea why the ground through pin 30 of my ecu won't cause the relay to close?

Thank you!

[kjones6039]

Are you sure that Fidle is set up correctly in your spare ports settings?

Ken

[portmod7]

Are you sure that Fidle is set up correctly in your spare ports settings?

Ken

Here are a couple images to help you guys see what I've got going on, maybe it will help identify my problem.

I am not 100% sure I have anything set up correctly, I am VERY new at all of this, but I am learning I've searched, and searched, and searched... And best I can tell I've got everything hooked up and configured correctly. If there's anything else I can tell you, or show you to help you help me, please let me know!

Like I said above, I can jumper pin 85 on my relay to a chassis ground and the fan kicks on like it should. I can pull the relay out of the socket, change the "on" temperature in the port settings to below the current temperature and get connectivity to ground, and I can change the "on" temperature in the port settings to above the current temperature, and it breaks connectivity to ground. But the relay will not actually close/activate when the ECU (Pin #30 on DB37) shows connectivity to ground.

Is there a diode or something in the Fidle circuit that I have in backwards maybe? The only other thing I can think of is that when I first hooked up my fan relays, I was confused about the function of my relay block. Consequently, the coil side of the relay(86-Batt.+ and 85-Fan+) was powered all the time, closing the relay. So when the engine got up to temperature, and the Fidle port was turned on and it grounded, it may have fried something in my ECU because there was no resistance between the battery and ecu (87-Batt+ and 30-DB37 Pin 30)? A transistor maybe?

Thanks for the help guys!

[ChevelleFan]

Your spare port settings for FIDLE look correct -- meaning, looks pretty much the same as my settings that worked when my car was running. Fan should turn on over 45* and off at 35* by your settings.

Your testing steps look good. But just for the sake of it, have you tried a different relay? Some relays require a different amount of current through the 85-86 circuit.

-Dave

[portmod7]

Your spare port settings for FIDLE look correct -- meaning, looks pretty much the same as my settings that worked when my car was running. Fan should turn on over 45* and off at 35* by your settings.

Your testing steps look good. But just for the sake of it, have you tried a different relay? Some relays require a different amount of current through the 85-86 circuit.

-Dave

I have tried other relay's of the same type, but have not tried a different style. It's going to really bum me out if I need a different style relay, because anything else won't fit in the relay block I have... But I will see if I can come up with an easy way to test that. Thank you for the suggestion!

[trakkies]

Probe across the relay coil with a voltmeter when the valve should be on. You should get near enough battery volts - just a small drop due to the switching transistor. Most car relays will operate at 9 volts or so onwards.

[portmod7]

Probe across the relay coil with a voltmeter when the valve should be on. You should get near enough battery volts - just a small drop due to the switching transistor. Most car relays will operate at 9 volts or so onwards.

I will give this a try as well, thank you for the suggestion.

Anyone else??

[portmod7]

Hi guys,

I am going to try the troubleshooting tips suggested above tonight, but I wanted to post the ratings for the coils in the relays I am using in case you weren't able to find them on the link I posted. Maybe you could take a look and let me know if these relays should be working for me or not? Thanks again for everyone's help!

[kjones6039]

I am hesitant to ask, but I am curious.............

Why not use a standard universal automotive relay and dispense with the guess work??

They are available (as are the connectors) everywhere for cheap! Not to mention they are used extensively by many MS users.

As I said, just curious................

Ken

[portmod7]

I went with this style of relay because it's what fits in this fuse/relay panel. It's got enough room for my headlight relays, fan relays, associated fuses, and is weather-tight. The headlight relays are working flawlessly. These are an automotive relay(http://www.songchuan.com/db/pictures/Ad ... 522687.pdf), similar ones can be found in many newer vehicles, and at automotive parts stores like Autozone(expensive ~ $15). Maybe they are a little more modern than what you are used to seeing? They cost me $2.91 each when I ordered the rest of the electrical parts I needed for my project. Seemed like a pretty good setup, especially for under the hood and where I placed it.

[trakkies]

The drive transistor is a ZTX 450 which is capable of sinking 1 amp, and the circuit is limited to 0.7amp. Your relay is taking only approx 0.1 amp so it's unlikely you have damaged anything.

Does TS show the Fidle in operation when the coolant temperature is low enough?

[portmod7]

Ok, I am at my shop now. I just got done with the above recommended troubleshooting steps...

I am only getting 0.43V across the relay coil with the Fidle port turned on. Battery voltage is 12.03V.

I also jumpered a more "common" style relay to the circuit, and it will not close/activate that relay either.

I am sure the port is turning on and off correctly, I can break connectivity to ground on my relay ground(pin 30 on the DB37, Fidle circuit) by changing the coolant temp threshold value in the "output port settings" dialog in TS. Current coolant temp is 43*F. The port turns on and I have connectivity to ground if I set the threshold value to 30. I lose connectivity and the port is indicated as off if I set the threshold value to 60.

I suspect there has to be a problem on my PCB, burned up something when I had the fan relay hooked up incorrectly at first.

Any ideas? Thanks again for all the help!

[trakkies]

Remove the processor, and link pin 20 (+5v) to pin 34 of the socket. If the driver circuit now closes a relay, it's ok. If not, first examine the PCB with a magnifying glass for solder bridges at the transistors Q4 and Q20 - the pads are very close.

If ok replace both transistors - they are so cheap it's not worth trying to check them. To remove use a bit large enough to heat all three leads at once and make sure the solder has melted before trying to remove. It they don't come out easily, add some solder. The important thing is not to damage the PCB by using force - the old components don't matter.

Then clean up using solder braid. Now check all the tracks for continuity before fitting new transistors.

Use a small tip (2mm or so) to solder the new transistors and small diameter solder - 0.7mm diameter is best. Keep the iron applied for a count of two seconds after the solder has melted, to make sure it gets to the other side of the PCB. Again, check carefully for solder bridges.

[portmod7]

Remove the processor, and link pin 20 (+5v) to pin 34 of the socket. If the driver circuit now closes a relay, it's ok. If not, first examine the PCB with a magnifying glass for solder bridges at the transistors Q4 and Q20 - the pads are very close.

If ok replace both transistors - they are so cheap it's not worth trying to check them. To remove use a bit large enough to heat all three leads at once and make sure the solder has melted before trying to remove. It they don't come out easily, add some solder. The important thing is not to damage the PCB by using force - the old components don't matter.

Then clean up using solder braid. Now check all the tracks for continuity before fitting new transistors.

Use a small tip (2mm or so) to solder the new transistors and small diameter solder - 0.7mm diameter is best. Keep the iron applied for a count of two seconds after the solder has melted, to make sure it gets to the other side of the PCB. Again, check carefully for solder bridges.

Thank you trakkies. I'll give this a shot tonight and see what I can figure out. Just to confirm, I would leave my PCB connected to my engine harness, power it up, link pin 20 to pin 34 with the processor out, and it should trigger my fan relay, correct?

[trakkies]

Yes that should be fine.

[portmod7]

I have performed the test you described, it did not trigger the relay. I also do not have solder bridges. So I have a couple transistors on the way. I searched all over town today trying to find some with no luck. So it will probably be the middle of next week before I get to see if we've correctly identified the problem and fixed it, but I feel confident that we are on the right track. Thanks to everyone for their help! I'll update you when I get the new transistors in.

[trakkies]

Even living in London I don't usually bother trying to buy electronic components at a shop - most that once sold this sort of thing have closed, or changed what they sell. But lots do next day post when ordered on the net or by phone.

I'm 90% certain this will fix things and the good news is the processor is likely fine.

[portmod7]

Ok, my parts came in sooner than expected, so I've got the old transistors out and the new ones in.

Also, before I pulled the old ones out, I tested the circuit again by jumping processor pin 20 to pin 34 as described above. This time I tested the voltage across the relay coil and got the same results as before.

After pulling the old transistors out I decided to test them as described on this page: http://www.elexp.com/t_test.htm. I determined that the B-E junction was shorted on both Q4 and Q20. The B-C junction of Q20 showed to be "open" (not sure what that means?) and the B-C junction of Q4 was good.

I will get to test the function of the fans tomorrow evening, I will update after I do that. Thanks everybody!

[trakkies]

I'm surprised you don't have a DVM with a transistor test function - most do. You simply plug in into a socket, set the DVM to PNP or NPN, and it reads the gain of the transistor. No gain no work.

[portmod7]

I'm surprised you don't have a DVM with a transistor test function - most do. You simply plug in into a socket, set the DVM to PNP or NPN, and it reads the gain of the transistor. No gain no work.

Ha ha, you are correct! I never even noticed or payed attention to it before. I am VERY new to all this electronics business, I've never even had the small hobby kits. I've learned a LOT with this project, and I just learned some more, thank you! My cheapo DVM (http://www.circuitspecialists.com/low-c ... meter.html) doesn't even come with a real set of instructions.

Just to update this thread, IT WORKS! Replaced the transistors and everything is working great. I've been working very hard on this project for the last year and a half, and it's finally time to take it out on the road! Thanks again to everyone for their help!

And trakkies, I feel compelled to tell you I visited the UK back in September and absolutely loved it! My wife and I spent most of our time in North Wales with some friends of her family(it was her second trip over), but we did make it to London for a few days too. We continuously talk about when we will go back, and half-heartedly talk about moving over there for good. We were astounded by how friendly the people are over there. There's beautiful scenery everywhere you go and the history that survives is mind-blowing.