328 solenoid click but starter not turning -- starter or solenoid?

Drove my 328 yesterday with no issues. This morning, it did not start. When I turned the key, I heard a single prominent click from the rear (presumably the solenoid) and the fuel pump ran, but the starter did not turn. Battery voltage was OK. To troubleshoot further, I removed the fuse for the fuel pump and then cycled the key a bunch of times. Finally the starter turned. Tried a bunch more times, and about 30% of the time the starter would turn (the other 70% I'd just hear the single solenoid click). So I put the fuel pump fuse back in and rolled the dice -- after a few key cycles, the starter turned and the engine started.

Based on this, I suspect either the solenoid is failing and not energizing the starter, or the starter has some dead spots (could be armature or brushes really). Since I always get the click, I think that eliminates upstream issues like the key switch or control wiring. I do plan to check the heavy positive cable feeding the solenoid, including the connector under the car, and also check grounds. Would be good to rule those out, but I think the symptoms point to the solenoid or starter. What do other folks think based on what I described?

Looks like I can source a ZM573 solenoid to replace the NLA Bosch unit. If the starter is bad, I'd either need to find a rebuild kit for the original Bosch unit or switch to a third-party gear-drive starter.

 

Wow, really? That would defy my troubleshooting logic completely.

 

I will check the wiring today and look for any obvious problems. Next time I catch this problem in the act, I will measure voltage coming into the solenoid from the battery. Also will check voltage at the solenoid trigger input #50. If it's low, I can work backwards along that white wire to see where I may be losing juice. From the wiring diagrams I see it pass through connector 169 in the left rear wheel well and connector 135 in the passenger footwell.

Three years ago when I did some service through the left rear wheel well, I cleaned all the pins on that 169 connector, added contact enhancer, and made an effort to secure the connection with zip ties since the connector looked cheesy for something so important to many functions -- looked like a problem waiting to happen. I would hope that is not the culprit. But I was just in there again two weeks ago when refilling the transfer case gear oil and it's possible that connector got bumped when I put the wheel well cover back in. Haven't had any problems starting until yesterday, but you never know.

Thanks for the help everyone!

 

Steve, I want to say that it was a pretty hard click, but I have no reference since this is the first time I heard the solenoid without the starter making noise and drowning everything else out. Also the first time I have heard the new fuel pump running in the 2+ years since I replaced the original. My gut impression is that it's a problem with the starter and repeated key turns and motion of the solenoid is bumping it enough to get past a dead spot on the starter (similar to the old hammer-tap trick). But that is based on past experience with other cars, and the advice here was a good reminder that there are well known wiring glitches on the 308/328 that can cause issues on the upstream control side of the solenoid. So I will take my time to debug this more thoroughly before jumping to conclusions.

 

Well my car has stubbornly been starting without issue. I was hoping to catch the problem in the act, and have two multimeters and a bunch of test leads ready. Will give it another couple days before I go poking around the tedious way.

 

Wanted to bump this back up -- my 328 has been starting fine for about two months since the original incident and I never had a chance to diagnose it further. But this morning it finally happened again. Three attempts and nothing but a click. On a hunch, and because I really needed to move the car out of the way for a garage door repair, I gave the dashboard a Fonzie slap on the fuse/relay cover panel (the panel that has a "GTS" logo). Sure enough that cured the problem and it cranked and started fine. So I think this indicates that I indeed have a wiring issue or bad contact somewhere in the vicinity of the footwell connectors or fuse/relay area. I'll do some diagnosis when I have time, but I suspect may be easier to just re-wire the line coming off the ignition switch and bypass the old connectors/etc. Will see when I dig into it.

 

Wanted to bump this back up. Car has been starting fine for the last 10 months. Yesterday the problem appeared again -- turn the key to start and the fuel pump runs but the starter doesn't spin. So I went out this morning to do some troubleshooting in the wiring upstream of the starter solenoid. First I jiggled a bunch of relevant wires/connectors with no success. Then I checked and cleaned the white wire connector at the key switch and in the footwell (all the connectors looked fine but I brushed on some De-ox-it terminal cleaner/enhancer since I was in there). Based on testing output from the key switch #50, related output from the footwell connector (pin #1 goes to starter solenoid, pin #2 goes to cold start electro valve), and continuity from the key switch to related the footwell connectors, I believe everything is OK up to the point where the wire exits the footwell connector.

Partway through my testing, the starter spontaneously began to spin, but only about once out of every five tries. Under cranking load, I was able to measure ~10.5V coming out of the key switch and footwell connector, which should be acceptable for voltage under cranking load (without load it was ~12.7V in both locations).

Despite the starter intermittently spinning and foiling my attempts to be methodical, I believe the problem must be somewhere downstream of the footwell connector, either the left rear wheel well connector or the starter solenoid itself. I did try jiggling the rear connector through the engine bay earlier in my troubleshooting, to no effect, but now I think I need to get into the wheel well and probe the relevant connector pin (#13) directly. From there, work my way to the solenoid.

If anyone has any suggestions/feedback based on what I know so far, be glad to hear it! Thanks!

 

Thanks, good question -- I wasn't paying attention to the click today but pretty sure something is still making a click. I'll start testing voltage at the starter & solenoid pins tomorrow and see what I can learn.

 

Well, my "macchina incorreggibile" as I am calling my 328 now, cranked fine today, in fact I could only get it to fail about once out of 20 tries. Not consistent enough to troubleshoot voltage but I did drive the car into my shop and put it up on Quickjacks. Upon testing the 15-pin connector in the rear left wheel well, I think I found the culprit. I could not get continuity across the pins at position #13 which carry the +12V solenoid trigger, nothing at all. I double and triple checked because I don't know how it would start sometimes if that pin wasn't connecting, unless maybe installation puts a slight amount of pressure on the wiring that helps sometimes.

I'll put some pics below, first here is the harness-side connector with female pin #13 circled:

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In person, that pin and a couple others are spread open more than some of the other pins, but it's not a huge difference and doesn't look very dramatic in the photo. Here's the engine-side connector with male pin #13 circled:

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I tried getting in there with a magnifying glass to look for signs of arcing or scoring, but couldn't see much. So this isn't the most convincing evidence but for sure I wasn't measuring any continuity across that pair of pins.

I didn't test any other pins, but suspect more are either problematic or will be. So it probably makes sense to replace or bypass the entire 15-pin connector. I need to look in my parts pile to see if I have any suitable Deutsch connectors, but I do have a huge stock of marine-grade blade connectors so I may just use a bunch of those. If anyone has better ideas or has replaced this connector, please let me know. It doesn't look easy to de-pin, otherwise I'd try to see if I could massage the existing pins into better condition.