944Hybrids: 924/944/968 and 928 V8 Conversions
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HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Fan Relay Problem

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Fan Relay Problem Empty Fan Relay Problem

Post  944-v8 on Sat Sep 12, 2015 11:17 pm

Hi Guys: My fans started getting very quirky. Passenger not running then neither running. Used the clarks-garage test your relay setup and nada. So I took it apart and used contact cleaner on the internals and sprayed the fuse box connector side. Got voltage one fan and low voltage on other. I would like to keep the Porsche setup for fans.  I may have a bad relay. Tried another relay and didn't seem much different. I looked under the fuse box and didn't see any corrosion, Is this a prevalent problem and what do you folks due to fix it besides going to 3 relays, I also don't know if the 3 relay solution controls the fans for A/C . Where would ecu get a signal from?

Also I need a new fan plug/connector. Local Porsche dealer parts dept said not available. Does anyone know where I can get a replacement connector for the stock 87S radiator fans connector?
Thanks

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Fan Relay Problem Empty Re: Fan Relay Problem

Post  948 on Sun Sep 13, 2015 9:39 am

Assuming your system is using all of the stock Porsche fan control circuitry, have you tested the functionality of the thermo switch? It is what controls the fan relay.
http://www.germanautoparts.com/Porsche/1987/1021/4/4768/0
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Post  944-v8 on Sun Sep 13, 2015 1:37 pm

Thanks for the reply: I eliminated the switch in these tests. Shorted pins 1-3 for hi speed and 1-2 for low speed on the thermoswitch connector. My assumption is that all there is in this circuit is the relay , +12V and the fans + low speed resistors (with thermoswitch eliminated). I have modified the circuitry for the fuel pump using an external relay w/o problem. I trying to make sure I'm not missing something. It almost looks like hi resistance connections. The only connections I believe are through the relay. This used to work. Have you heard of any preventive or other maint processes for problems like this. I've seen other connections have oxidation/hi resistance issues in this car. I'm hopping to not have to pull the entire central electric (fuse Box) apart. I'm also not sure what methods are successful in cleaning the relay socket contacts.
Thanks for any thoughts:

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Post  948 on Sun Sep 13, 2015 6:19 pm

Have you applied 12v directly to the fans? Also, have you determined if the in-line resistors are good, 0.9 ohms each?
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Post  944-v8 on Sun Sep 13, 2015 6:41 pm

Yes both fans run full speed when 12v applied. Didn't chk the resistors because I couldn't get the fans to both run full speed with pins 1-3 shorted on thermo connector. In that case they should both run full speed. Clarks-garage tests for a bad relay. One lead would have 12v (driver side) and not the other. Then the voltage dropped to 5V. I decided to stop there and let the contact cleaner soak and query the the board for known issues.
Thanks:

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Fan Relay Problem Empty Fan wiring

Post  simon123 on Mon Sep 14, 2015 9:37 am

This is what I used, the LS1 ECU controls the fans.
(I'm assuming that you are using a LS series engine)

Fan Relay Problem Fan_wi10

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Post  Rich L. on Mon Sep 14, 2015 9:52 am

Bummer about your trouble. My '87 fan system quit running on low speed, would still do high with both fans. A new switched fixed it. I do hear these systems are often problematic. Good luck.

Rich
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Post  944-v8 on Mon Sep 14, 2015 11:20 am

Thanks Guys: Re-checked after contact cleaner soak--same. I'm looking for a new relay and then I'll cave in and go 3 relays, I do have an Lt1, so I hope the fan wiring is the same from the ECU. I'll re-post if I finally decide to go 3 relays. Also, what happens with the A/C setup if I go 3 relays. Do I splice the A/C request line and feed the ECU? Still looking for a replacement connector from the harness for stock fan motor.
Thanks again for the replies.

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Post  spence on Mon Sep 14, 2015 4:18 pm

944-v8 wrote:Thanks Guys: Re-checked after contact cleaner soak--same. I'm looking for a new relay and then I'll cave in and go 3 relays, I do have an Lt1, so I hope the fan wiring is the same from the ECU. I'll re-post if I finally decide to go 3 relays. Also, what happens with the A/C setup if I go 3 relays. Do I splice the A/C request line and feed the ECU? Still looking for a replacement connector from the harness for stock fan motor.
Thanks again for the replies.

I have a Lt1 and thats how I have my fans wired. I don't have A/C, so I'm not sure what you'd do there.
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