When I jump the low speed fan relay, both fans run at low speed. When I jump the high speed relay, only the passenger side fan runs at high speed, and the driver side fan does not run at all. When I connect 12v directly to either fan, they run at full speed.
In VCM Scanner, when fan 1 is set to On, both fans come on at low speed. When fan 2 is set to On, only fan 2 runs at full speed, mimicking the jumped relay setup. It seems that fan 1 On is equivalent to fan state 1, and fan 2 On is equivalent to fan state 2. Is this how they are supposed to operate?
Low speed uses only one output pin and one relay (low speed), For high speed, both outputs have to be on at the same time and all 3 relays activate. The 3rd relay is there to change the wiring arrangement from both fans in series (low) to both fans in parallel (high).
For some reason posting a .pdf that contains a single image reminds me of the olden days of a MP3 file broken up into multi-part-.rars inside a .zip file.
How are you jumping the relays - at the output terminals (probably not a great idea, and not really going to give you any useful info for diagnosing a problem), or by grounding the coils (mimicking what the two ECM pins do)?
If you have a problem you're trying to solve it might help to say what that is, and post a file so your settings can be checked.
All 3 relays would need to be jumped from 30-87 for it to re-arrange the wiring to put both fans in parallel and get both fans at high speed.
For low speed Output 1 only turns on the left relay, which runs both fans in series, or each fan gets half voltage. High speed is Output 1 AND Output 2, which turns on ALL 3 RELAYS at the same time - the middle relay removes the series connection (opens the 87a term), and then the left relay and right relays each supply full voltage to both fans.
I would be checking for ground at the two relay control outputs at the ECM first instead of jumping relays. I don't really see what question would be answered by jumping the relay output terminals.
Reply With Quote
