No Distributor Reference Pulse - Need Help Troubleshooting!

Maintenance and Repairs
1

I’ve been having some issues with my Chevrolet, specifically related to the distributor reference pulse. It seems like I’m getting a no-pulse scenario that’s affecting the engine’s performance.

Here’s what I’ve done so far:

  • Checked all the fuses and connections in the ignition system.
  • Inspected the distributor and made sure there’s no visible damage or wear.
  • Scanned for error codes and found Code 12, which I read is related to this issue.

My Questions:

  1. What could be causing the no reference pulse? I’m curious if there are any common culprits that I should look into.
  2. Are there specific areas within the ECM that tend to fail? I’ve heard murmurs about some connections being problematic.
  3. Any recommendations on achieving a proper fix? Whether it be testing a certain component or what tools best diagnose the problem.

Additional Info:

  • My vehicle is a 1988 Chevy Caprice.
  • I’m not super experienced with electrical work, so any step-by-step guidance would be greatly appreciated.

Looking forward to your insights! Thanks in advance for any help you can provide.

2

I’m assuming you already checked the obvious like blown fuses? A lack of distributor reference pulse could often point to a faulty crankshaft or camshaft position sensor.

6 Likes
3

Thanks for the tip! I also heard that the ignition module could cause similar issues. Has anyone had experience with that?

5 Likes
4

Yeah, diagnostic tools like an OBD-II scanner can help pinpoint problems. But sometimes, you might need an oscilloscope to check the pulse signals more accurately.

5

Good idea! I don’t have one, but I can borrow a multimeter. Can that work for diagnosing basic issues?

6

Using a multimeter can help check for continuity in the wiring, which is a great first step! Just make sure you’re getting the right thresholds of resistance.

7

So, if the wiring checks out but you still have no pulse, what would you recommend trying next? This feels like a giant puzzle!

3 Likes
8

You might want to look at the timing belt too. If it’s slipped, it could throw everything off!

2 Likes
9

This is becoming quite the troubleshooting journey! Remember that sometimes the simplest fix is hidden.

10

What do you mean by ‘the simplest fix’? Like the battery maybe being dead? Sometimes it’s just a little oversight.

11

Right? I’ve seen people troubleshoot for days only to find out they left a connector unplugged!

12

Speaking of oversight, I forgot to mention checking all ground connections! A bad ground can totally mess with signals.

13

Could’ve just used magic to fix it, right? Just kidding! But honestly, troubleshooting can be a nightmare sometimes…

7 Likes
14

No kidding! It’s like a horror movie where the answer is always right around the corner and just out of reach.

15

The experience can indeed feel like a rollercoaster! At least once you figure it out, you’ll have a great story to tell. What are your next steps?

16

I’m experiencing the same issue! Make sure to check the wiring from the distributor to the ignition module. A broken wire can easily interrupt the pulse.

6 Likes
17

Great advice! It’s also worth checking the ignition coil; if it’s faulty, it may not produce a reference pulse.

18

Have you checked the distributor pickup coil? It’s a common failure point. If it’s bad, you’ll need to replace it to restore the pulse.

7 Likes
19

I had a similar issue, and it turned out to be a poor connection at the ECU. Always inspect every connector to rule out bad contacts.

20

Absolutely! And using electrical contact cleaner can help. Just spray it on and make sure the connector is dry before reconnecting.

2 Likes