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1st Time 1st Gen! Got a issue I’m trying to figure out... ECM?
1st Gen. Ram - All TopicsDiscussion for all Dodge Rams prior to 1994. This includes engine, drivetrain and non-drivetrain discussions. Anything prior to 1994 should go in here.
1st Time 1st Gen! Got a issue I’m trying to figure out... ECM?
He everyone. Just put my truck (Junior) on the road for the first time today! Bought it in July, it’s a 93 LE 5 speed, JR has 131k on the clock. I have a lot of work to do, and as of now it’s bone stock right now. I know the ECM voltage regulator is not working as it already has an external regulator mounted in the engine bay. I did order an alternator conversion so it will be self regulated.
I do have one issue I’m trying to track down that I believe to be ECM related. The speedo, cruise control, grid heater and tach all do not work when the truck is first started. They all eventually come to life after driving for a while (5-10) minutes. I’m thinking maybe a ground issue? It’s odd that it just sorta starts working after a while of driving. Any thoughts? I’ll try and track it down tomorrow , but I wondered if anybody may have a bit of direction for me. Thanks and I’ve already learned a lot just from poking around in the group.
I think that a bad/loose ground is likely. It sounds like the metal is expanding as it heats up and making the ground good, until it cools off again...Mark
Might want to follow Mark's idea above. As stated a million times on this forum, the grounds in our trucks are NOTORIOUS for being gunked up. I disconnect mine at minimum once a year, sometimes twice a year. That means ALL of them. The ones on the firewall, radiator support, engine block, engine block, etc.
Once the grounds are all cleaned up, and you find you're having a similar problem, look at the 3 relays on the fenderwell driver side. Believe it or not, relays do go bad. Disconnect them, make sure the ends are clean and not all gunked up, and rotate them in sequence, meaning move the same style relay to the other position and see if it fixes your problem.
Fusable links can be a real pain as well, and those are located in the same area. They can be "intermittent" as well, which why replacing them with the maxi fuses is a good idea.
Do as above....grounds are very important. But it sounds to me like your CPS is not working properly, or one of the 3(?) connection points along it's circuit is fouled up.
So I spent some time under the hood of my truck... the PO didn’t do me any favors. 😒 The wireing is truly a mess. I’m gonna have to go through the whole engine bay harness wire by wire. I’m sure it’ll be better off doing this in the long run.
Your headlights should be separated onto relays. The fuseable links are junk, and can be upgraded to maxi fuses.
the heater blower motor can be separated as well, but ive never done it and have had no issues.
Most of these are dictated in the sticky, headlamps being priority as they draw their power through the ignition switch, and fuse panel above your brake pedal. Theyre known to ( the fuse panels ) melt, and catch fire....
I had a similar problem. The crank shaft sensor was not working. But the problem was the 8 volt supply from the ECM. So check the connector on the crank sensor to see it there is 8 volts DC there.
If there is 8 volts DC plug the sensor back in and connect between the signal wire and ground with a meter with the motor running. On a AC scale you should see 200 mill volts ac.
Check the air gap on the sensor 50 thousand.
DId you ever fix? I have similar issues .. been in multiple shops... Spent endless hours reading these forums and working on it myself.. There is so many speedo/no charge/fuses blow posts on here its crazy. My truck has had electrical gremlins like this for the 2 1/2 years I’ve owned it! Driving me nuts! (I’ve traced wires, poked around with meters, cleaned grounds, new alt, multi-function switch, brake light switch, rear sockets, external regulator, 100 burnt fuses).
Currently trying to figure out how to test/adjust spacing for ESS and researching CPS..
Hope I didn’t scare yah and your not experiencing other electrical woes.
No I haven’t yet. It’s been too cold and snowy to mess with for now. I’m planning in the spring to go through the entire electrical system and get JR back to where he should be. It’s gonna be a big undertaking, but one that I feel is going to be worth it.
01-05-2019, 08:58 PM
