CAN BUS Troubles - Jeep JK fitted with Hemi engine

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ronw38
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Re: CAN BUS Troubles - Jeep JK fitted with Hemi engine

Post by ronw38 »

Kona and Liviu are on the money. Try this, don't take any measurements or make connections from the OBD2 plug, scope can at the most accessible module [usually ABS]scope at 500ms division plus/minus 10v free running no trigger get familiar with looking at a good normal pattern when vehicle is OK- idle voltage 2.5v Hi 3.5v Lo 1.5v spikes and noise are normal pause and zoom just to observe general packet patterns don't look at bits or try decoding at this stage once you know what a good pattern looks like take captures when the system faults you should see a change in voltage levels pulled up/down and or pattern distortion, time to un plug and re plug modules one by one to see if a good pattern returns any with a terminating resistor may cause extra distortion but should return the pattern if faulty? wiring/connectors may be shorted to ground/power, if the signals disappear raise above battery voltage to 20v. As the lads have said you cant scope at the OBD plug when the signals go through a gateway to the plug early systems and some makes went directly to the plug hence the confusion. Cheers Ron

French Chris
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Re: CAN BUS Troubles - Jeep JK fitted with Hemi engine

Post by French Chris »

OK Thanks for your help guys,

I will try that.

French Chris
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Re: CAN BUS Troubles - Jeep JK fitted with Hemi engine

Post by French Chris »

Thanks for your advice Ron.

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