Skip the auto shop - Our mechanics make house calls

Q: I have to actually use a heater on th ECU PROM to get my vehicle to start when its cold.

asked by on

It's a 1993 dodge ram D150 3.9 6 cylinder. Has 209,000 miles. I have to put a heater on the ECM PROM computer from 10 -20 minutes and than it starts to click and than once it stops clicking it will start. After it has been running a while it seems to be ok. When it sits depending on how cold it is it might not start again. Than you have to warm it up again.

Now if the weather is warm outside it appears to be ok and no problems with starting.

The other day it stopped completely and now it will not start. Before it stopped it was intermittent causing it to stall a couple of times. Now nothing at all. The engine does still turn over.

What do you think? Does the ECM PROM computer need replacing only? I have not tried warming it again.

My car has 209000 miles.
My car has an automatic transmission.

A: You have successfully diagnosed your truck....

You have successfully diagnosed your truck. It definitely needs a new ECM. Electronics are very sensitive to temperature. There are relays inside the ECM box that you are heating, which makes the contacts expand and create an electrical connection. This will happen with relays, capacitors, resistors and all sorts of integrated circuits.

When it comes to replacing your ECM, make sure you have the old one removed and take it with you to the parts store. You should have your VIN number available as well. The old ECM will have serial numbers that will make sure you get the correct ECM for your truck.

This repair isn’t found in the inspection online, but most likely there will be a technician in your area that can replace it for you. I will have customer service contact you to help you out with this.

Thanks for your question.

Good luck!

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car will not start

Hi there. Thanks for writing into about the starting issues with your 1993 Honda Civic Del Sol. After reading your question, it appears that you might have a problem with the ignition switch itself if others are able to start...

Q: Is it dangerous to drive while reduce engine power light is on?

The engine control module (ECM) has a safety feature built into it when the ECM detects a major fault in the sensors or actuators that can cause the throttle opening to be limited. With the reduced engine power and throttle...

Q: Misfire on cylinder #1

Hello. A flashing check engine light is an indicator that the computer has detected conditions that are harmful to the vehicle's emission system components. Continuing to drive with a flashing check engine light can result in damage to emissions system,...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.