Registered with the forum specifically for this stubborn problem, hoping someone has seen it before.

2008 Ram, 100k miles/144km, Canadian truck. 49 times out of 50, when I turn the key, I get a quick click out of the starter and then nothing. If I apply power directly to the starter solenoid it'll turn over, and if I do this AND turn the key, truck starts. It'll also start if I use my SnapOn scanner and turn the Double Start Override Relay to the ON position. The engine was replaced but done by an expert, and it runs just fine.

I have checked the power "trigger" wire from the TIPM to the starter. I get the quick flash on that line, and again if I send power down it it'll crank just fine. There are no related codes, just a RADIO COMMUNICATIONS LOST due to an aftermarket radio. I have full control over the rest of the systems when accessing the TIPM (Washer control, lighting, etc.)

My suspicion is the TIPM "relay" (it's solid state, I pulled the circuit boards out for inspection) is faulty and not allowing proper current flow. I did not yet try disconnecting the power wire from the starter relay and seeing if without a load do I get continuous power.

Thoughts?

 

it does sound TIMP "relay" related to me also. Only because you know your battery is good because you bypass the ignition switch and jump the starter. That also says the starter is good and works. But being everything else works through the ign switch, sounds relay related to me. Contacts could be corroded or energizing coil weak.

 

So I disconnected the starter 'trigger' wire from the starter solenoid and hooked a test light, and it lights up. If I hook it back to the starter, it clicks but power is quickly removed by the TIPM. I hooked a relay in line, so the starter wire trips the relay, which powers up the starter solenoid, in case the starter solenoid was drawing too much current and shutting down. No dice - exactly the same. It's looking more like the computer thinks the engine has started with that initial kick, and is shutting down the starter solenoid power.

 

Also I just noticed that if I leave the key in RUN but do not start, after 15 seconds and the Electronic Throttle light goes out, the CEL flashes 10 times and then stays solid. The truck is currently not cranking.

 

If the CEL is on then you have DTC codes stored and you need to find out what they are. Can you check them with your SnapOn scanner and post them?

 

That's the fun part... there's no codes. There's a code for loss of communications to the radio (customer has an aftermarket radio installed) and one for the RF headlight low beam (which I believe is burnt but it's not the issue I'm working on).

Here's a fun tidbit - if I get into functional tests and ACTIVATE the DOUBLE START OVERRIDE RELAY, the key will function to start the truck 100% of the time.

This is looking more and more like a computer logic issue.

It's worth mentioning that I replaced this engine last week, but it started immediately follow and ran fine for 2 days. This is a new issue. Customer neglected his oil changes for 100k, truck delivered with no oil pressure and a knocking bottom end. Engine is from an '07, with the cam and crank sensors taken from the old engine so they fit the harness. Knock sensors are '07, intake, TB and injectors are all original.

 

Missed tightening a ground strap against the engine block. When I went to crank, the amount of current needed to turn the starter "starved" the TIPM of sufficient ground path to keep the relays closed. Tightened ground strap, starts every time now.

Did cost me $50 for another guy to have a look at it.

 

Well good. I left my office only to come back and see you resolved it. Good find and I know you are happy now.....LOL

 

I have the same problem on a 2011 Hemi. I was only able to start it by turning the DSO relay on using the scan tool.
Ended up being a loose ground strap to the engine block just like you said, you saved me a lot of time!

 

This thread is almost 15 years old...