DDEC CEL and SEL wiring?

[Iceni John]

Do the DDEC wires 419 and 509 that feed the Check Engine and Stop Engine lights ground when the lights are on (like the 508 Engine Brake wire does to turn on the Jake brake)?   According to my schematic the CEL and SEL are also fed by 439  -  is 439 a 12V positive feed to the ECM, or is it just a signal to turn on the ECM?   439 appears to be switched by the DDEC power relay when the Ignition is on, and is supplied by 99 which is a 12V positive feed from the batteries.

The reason I'm asking is because I want to put a duplicate CEL and SEL on my rear start panel, and if I can feed straight off the ECM's wires 419 and 509 it would save me having to instead run 50 feet of 2-core wire all the way from the front.   I just don't want to bugger up anything by having more loads on 419 and 509 than they were intended to supply, or risk doing Bad Things to the ECM.

Thanks, John

[Bill Gerrie]

You have it exactly right. The 439 is a 12 volt positive line. CEL is 419 and the SEL is 509.

[Iceni John]

OK, so 419 and 509 are grounded when the lights are on.   However, is 439 the actual 12V power to the ECM, or is it just a trigger or signal for the ECM to turn on, assuming it gets its actual power from elsewhere?

Thanks, John

[Bill Gerrie]

439 is the 12 volt power to the computer from the ignition switch. There are several power lines to the computer direct from the batteries but 439 is the one that turns the computer on. The CEL and SEL are grounded through the computer to turn them on when a code is present or when you first turn on the engine.   

[Iceni John]

Excellent, thank you!   I'll see if there's a way I can tap straight into 419 and 509 at the ECM's plug to avoid me pulling wiring under the bus (no fun at all).

Thanks for your help.   All I have is a very basic overall DDEC schematic that doesn't go into much detail  -  it seems rather half-arsed to me, drawn by someone at Crown who was dyslexic, or at least wasn't good at spelling!

John

[Bill Gerrie]

John
Email me at retiredbusnut at yahoo.com   I couldn't attach the drawings of the light locations. File too large. The total current draw for the CEL is 1.5 amps and the total current draw for the SEL is 1.5 amps. You will have to size your lights accordingly to stay within the 1.5 amp limit.