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Too fast of an idle.

ak diesel driver

ak diesel driver

6.5 driver
Messages
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Location
alaska
This is on my 94 plow truck. Idles at about 11-1200 rpm. When I first start it cold it idles even higher and then goes down to the 11-1200 rpm after it warms up a bit. I'm thinking of replacing the ECT sensor in the crossover is there anything else to check. Seems odd to slow down after the initial warm up but not more later.
 
I would definitely look at either a bad coolant temp sensor, bad connection at the CTS, or a bad/broken ECM ground. If you have a scanner it would narrow down where to look alot quicker.
 
So I changed sensor with another used one I had on hand and no change. Any idea where to start looking for a bad ground. PCM connector?
 
So I decided to jumper the connector and when I did I got a reading of 304* so I disconnected the jumper and back to -34.4. so I plugged it back in and now it works. Don't know for sure what it was but I suspect the connection was not good and messing with it cleaned it up a bit.
At least I know where to look if it acts up again.
 
The pins on the coolant temp sensor are not very good quality. They're not coated like the ECM pins are. I've had to replace several before because of corrosion.
 
It's really common actually. Just that most people don't notice or ignore it (because they don't have a scan tool to see the issue). The pins lose tension and don't make good contact. Replacing that pigtail or the entire engine harness does wonders.
 
quadstar87 said:
It's really common actually. Just that most people don't notice or ignore it (because they don't have a scan tool to see the issue). The pins lose tension and don't make good contact. Replacing that pigtail or the entire engine harness does wonders.
Click to expand...
Made a big difference on the electricals under the hood when I cleaned every connector with a dental file. A real PIA while I was doing it but I believe it has paid off.
A 4X4 laid atop each battery and a 2X6, 8, 10, or 12 laid across them makes it mighty comfy to lay down on while performing such a function too. LOLOLOL All I had was a 2X6 and I think a 10 would have been much more roomier. LOL
 
MrMarty51 said:
Made a big difference on the electricals under the hood when I cleaned every connector with a dental file. A real PIA while I was doing it but I believe it has paid off.
A 4X4 laid atop each battery and a 2X6, 8, 10, or 12 laid across them makes it mighty comfy to lay down on while performing such a function too. LOLOLOL All I had was a 2X6 and I think a 10 would have been much more roomier. LOL
Click to expand...

We learned over the years and just use our new engine harness now. It runs above the intake so you can yank the old one out, send it to copper recycling can, and have all-new installed in 5 minutes flat. Don't forget a motivational beer.
 
One to motivate you to start the job, one to keep you motivated during the job and one for all that great motivation you showed after the job!

And yes, after burnishing the contacts of the male and female connectors, a good shot of silicone dielectric grease into the female connector half contacts before reassembly does WONDERS for preventing any oxidation/corrosion for years to come, even on a new part or harness, and much easier disconnecting of the halves, if needed, in the future. I swear by the stuff on things like headlight connections, starter solenoid energizer connection, the alternator field/tach plug, etc.
 
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