259D 636-2

[rickysenginerepair]

Hey all,

I've read through numerous posts about bad CPS and engine harnesses. I wanted to run something by people who are good with these.

I've done the Speed Timing Signal test that has been recommended. My voltage will fluctuate from 2.5v-4v, but I have voltage on both the power AND the signal with the sensor unplugged. I also have continuity to battery ground on all 3 pins. This is with key on. Does it make sense that I'd have a short to ground in that case? The test procedure does not mention continuity.

I'm confident that's all correct but I do not want to replace a harness unless it's 100% necessary.

 

[Nige]

Can you post a Serial Number please. There are about 10 different models of 259D and you may need an electrical schematic to test individual wires in the harness.

Is the attached the Speed/Timing test you have been performing.?

There is one place on the engine harness where it is pulled tight round a 90-deg corner (circled below) that is a good place to check, even if only to rule it out.

 

[rickysenginerepair]

FTL15967

Yes, that is the test I was referencing. I found it posted by you in another thread.

I saw that diagram also on another thread, but my concern was the engine layout does not match this machine. However, if it is a universal diagram and my main point of concern is the harness at the ECU bulkheads, I will check there.

 

[Nige]

Instead of performing a resistance test to establish continuity try testing individual wires by jumpering one end of a specific wire to machine frame ground then apply batt+ to the other end via a fused 5A test light. Any wire that will pass that level of current without going pop can be considered as good.

 

[Nige]

Apologies. This is your engine wiring harness setup. As a first step look at any location where the harness is pulled tight around a 90-deg bend.

 

[rickysenginerepair]

Cut all the zip ties near the ECU connector, no signs of chafing best I can tell given the limited visibility

 

[Nige]

The best I can suggest is to use the truncated wiring schematic contained in the speed/timing signal test document and individually test each wire in that circuit end-to-end (between the sensor and the engine ECM) using a fused 5A test light connected to batt+ at one end of each wire and with the other end of the wire connected to machine frame ground.