Headlight Control Module

[Vaughnc]

Hi all,
Does anyone know how/where to source a replacement Headlight Control Module GM part number 16525685?
My pop up headlights refuse to pop up consistently. I know there is voltage in the relevant connector and that the motors themselves actually work. The lights now only pop up when I jiggle one of the wires into the module connector. This suggests a simple connection issue. However I've carefully cleaned the connectors with limited impact. I took the module off and took its cover off to inspect the electronics within. Nothing obvious awry. I suspect a cracked solder joint which will be hard to see - that will explain the result of jiggling the wires.
Any help gratefully received!

[Fredjohn]

If you google the part no, there are lots of suppliers. Best bet though is SJ Sports cars: look here

Sorry can't help with any further repair suggestions other than checking the gear drive and associated bits, although your wiggling of the wires would rather exclude this issue.

[Tuga2112]

im going to refer you to this post where theres someone with an issue in that same control module.

i also had an issue in that control module and highjacked the thread to get help and at the end managed to fix mine.

back when that post was active. brit car nut told me he had a unit to sell if i failed to repair mine. so there is a small chance he may still have a spare unit.

I have studied the circuitry in that module a fair bit back then. and i believe re-flowing the 6 input pin solder joints would be a good and safe starting point. although i find it rather unlikely they would have a crack because to cause such thing you would have to pull the plug sideways really hard, given the location of the plug, that seems unlikely to happen as an accident while working in the area.

[Vaughnc]

Thanks for the replies chaps. I looked at the previous threads you indicated and the module photos. My module circuit board looks clean - nothing burned out - but I would have to look more closely to detect a cracked solder joint.

Just spoke with SJ Sportscars. They can supply a recon module in exchange for mine. However they think it may just be corrosion to one of the wires in the connector. Just jiggling it allows the headlight to pop up so seems plausible. I'll inspect that more closely than I did yesterday before I do anything else.

In those threads I noticed someone also had a problem with their rev counter going mad. I have seen something similar with mine registering an extra 500 RPM when I unhitch my seatbelt at the end of a drive. Could you suggest any other threads that I could read on this?

Thanks again

[Brit-Car-Nut]

Just for the record, I still have a few Headlamp Pod Lift Control Modules A100M6027F @ $100.00 + postage.

I believe Wayne (in Bahrain) also still has some stock

[Tuga2112]

one thing to keep in mind is that brit-Car-Nut is selling a new never used unit. while SJ is selling a "refurbished" unit. last time i checked it was cheaper to buy the new unit than to buy the service from SJ + the vat and all the postage costs associated.

[Brit-Car-Nut]

Thanks Jaoa.

If I don't say used or reconditioned, I am offering NEW parts. Unfortunately, the GM part has finally gone obsolete, so I only have a few new ones left. That is the similar for Ignition Control Modules. They are still available, but at almost 3 times the price as they are getting hard to find and now out of the wholesaler's inventories.

[Vaughnc]

Thanks guys. I removed all 5 wires from the input connector block - all are OK and clean. One was a bit loose so I slightly compressed all to ensure a good connection. Things worked after that initially, but soon the pods failed again and only work with a wiggle of the connector. So it seems there is a connection issue within the module. On that basis I'm best buying a replacement.
BritCarNut - could I arrange to buy one of yours? How would you like to arrange payment/shipping?

Thx, Vaughn

[Brit-Car-Nut]

eMail sent. If you don't get it within an hour, let me know and I will use a different eMail account.

[Vaughnc]

Thanks John. Email received and reply sent.

For anyone else reading this:-
I’ve solved the problem with my current module. I carefully inspected the solder joints for the main contact blocks on the circuit board using a watchmakers eyepiece. I found two pins on the 5-pin block with cracked solder joints. These were the outer two pins. Re-Soldering has (for now at least) resolved the problem. It’s enough to get the car through the MOT tomorrow - I hope!
I'm not surprised. Solder joints don't like to be moved especially as they get older. They can become brittle over time. I would guess that the connector blocks have been removed a few times in the life of the car - perhaps a bit too roughly - enough to put stress on the solder joints and crack them, Once the crack is open enough then the circuit becomes intermittent and eventually fails. That explains why jiggling the inbound wires allowed the pods to pop up as they created a momentary circuit. It also explains why mine have got worse over time. They were a bit temperamental when I bought the car. More recently they would fail after a long drive. I think that is caused by engine heat build up in the module expanding the crack just enough to break the circuit.

[texas2201]

Thanks John. Email received and reply sent.

For anyone else reading this:-
I’ve solved the problem with my current module. I carefully inspected the solder joints for the main contact blocks on the circuit board using a watchmakers eyepiece. I found two pins on the 5-pin block with cracked solder joints. These were the outer two pins. Re-Soldering has (for now at least) resolved the problem. It’s enough to get the car through the MOT tomorrow - I hope!
I'm not surprised. Solder joints don't like to be moved especially as they get older. They can become brittle over time. I would guess that the connector blocks have been removed a few times in the life of the car - perhaps a bit too roughly - enough to put stress on the solder joints and crack them, Once the crack is open enough then the circuit becomes intermittent and eventually fails. That explains why jiggling the inbound wires allowed the pods to pop up as they created a momentary circuit. It also explains why mine have got worse over time. They were a bit temperamental when I bought the car. More recently they would fail after a long drive. I think that is caused by engine heat build up in the module expanding the crack just enough to break the circuit.

Did you ever get a new module?

[esprit888]

There is one for sale on eBay, pricey though

https://www.ebay.co.uk/sch/i.html?_from ... e&_sacat=0

[texas2201]

There is one for sale on eBay, pricey though

https://www.ebay.co.uk/sch/i.html?_from ... e&_sacat=0

Sjs do an exchange one for £89 + vat postage


Really wanted a new one

Going to try resoldering

[donsladek]

Here's a link to a Corvette C4 Headlight Control Module repair page:

https://www.instructables.com/C4-Corvette-Headlight-Controller-Repair/

Don't know if the Corvette HCM is a direct replacement for the Elan's, but the modules are mechanically similar - don't know about the controller logic/connections.

Solder issues seem to be a problem for these controllers... If your DIYing a fix, this may be helpful.