1999 Dodge Grand Caravan Won't start in hot weather

I got a great deal on this van, and I love it, with one exception. On hot days (73 degrees and hotter) the van will not start if it has been parked in the sun; until the temperature returns down to around 61 degrees (usually overnight, but I have waited it out in the parking lot at work a few times).

When this happens, the lights and radio work fine; the starter motor will not engage. No click, no chugga-chugga vroom-vroom. Sad Curto.

Note: October through about May in North Carolina, this car is fine.

I have replaced the steering column (after replacing the clock spring); I have replaced the Power Distribution Center.

When the problem first surfaced two years ago, I had a mechanic install a wire directly from the starter motor relay to the solenoid. That was an expensive lesson. I’m not sure what the lesson is, so it was REALLY expensive.

So, I thought maybe the Auto Shutdown Relay. Nope… pull that out, and the starter still turns, so that is not my problem.

Now I am starting to thing Powertrain Control Module, or something else that could have a temperature-sensitive component.

What ideas do you guys have on this?



When turning the ignition in the start position can you hear the fuel pump humming?

If you’ve been driving for an extended amount of time and shut it off, day to fuel up, it’ll start when the engine compartment is heated up?

Squirt starter fluid in the throttle body and try to start it. If it starts, then it’s a fuel pump problem.

If it were a Honda, I’d say fuel pump relay…hey, they’re cheap.

Your post is a little unclear, but if the starter motor isn’t engaging … no rrrrr rrrr rrr sound when you turn the key to “start”, that’s the first problem you need to solve. Ask your mechanic to measure the two voltages at the starter motor (terminal to case) during attempted cranking. Let us know what is measured.

Good catch, George, gotta get the motor chugging first!

Thanks for all the replies! I have more to think about. Fuel pump… I’ll listen next time this happens… I think it is NOT the Auto Shutdown Relay, because I removed that relay and it would still crank.

The problem seems to be that the engine starter motor relay does not energize, and apparently this is grounded by the Powertrain Control Module. Like the circuit goes from
+Battery->ignition switch->engine starter motor relay->starter motor; so I think the relay is not energized (will be my first check next time.

That relay is energized through:
+Battery->Ignition Switch->Fuse->Engine Starter Motor Relay->Powertrain Control Module

I suspect the Pwertrain Control Module “Engine Starter Motor Relay Control” circuit is malfuntioning in hot weather somehow… but it does not really explain it, because the engine compartment would always be hotter than 80 degrees or so.

Unless the PCM is inside the passenger compartment?

In response to much of the thread so far: “the lights and radio work fine; the starter motor will not engage. No click, no chugga-chugga vroom-vroom.”

And yes, George caught it.

This is one of the most basic things for any mechanic to diagnose. You replaced the steering column and PDC? For gosh sakes why? There must be things that you’re not telling us.

Is this thing still on its original battery cables? Terminals? What has anyone actually checked or tested on the thing? Do you have access to a voltmeter? Have you ever tried shifting it to neutral and trying to start from there?

“the starter motor will not engage” when the car is warm.

This has the typical sign of a starter failing. If you turn the key, hear a loud click, but the starter doesn’t engage then you ususally have a starter motor failing. If you turn the key and hear nothing, you may have a starter solenoid failing, which is an assembly with the starter. So replace it.

This is easily checked with a voltmeter. Have your negative lead attached to the starter housing, and with the key in the “start” position, check for battery voltage at the main cable connection and the smaller cable connection. If you have good battery voltage at those 2, you have a bad starter.

What about the neutral safety switch?