Longish post….but I thought some folks might benefit from my cruise woes….

Almost three years ago, the cruise on my 1992 300D went out. Classic signs of a bad amp. So, trying to save some money, I elected not to have a through diagnosis of the cruise system, but instead focused on the amp (since, in the vast majority of cases with a bad amp, that’s all that’s wrong). So I could buy new, simply re-solder the old amp, or get a thorough re-build. I went with the rebuild through GDL.

I should say at this point that the only one I spoke to who was convinced that the actuator was likely bad too was Roy, the Fastlane tech guy….

When GDL rebuilt the amp, they noticed that the output transistors were blown and suspected that I might have a bad actuator (which I had not sent in for testing) as well…and of course could not be held responsible for subsequent damage to the amp. I elected to roll the dice and rebuild the amp anyway.

I had cruise for about three weeks then it died….so I resigned myself to living without cruise.

Last year I picked up a 1991 300D. Also had classic signs of bad amp. After mulling over various approaches (aftermarket cruise, cheap re-solder, etc…), this time I sent both amp and actuator to GDL for evaluation. And while I was at it, I sent the amp and actuator from the 1992 to see what was going on.

In the case of the 91, actuator was in good shape. So I did the actuator tune-up, had the amp rebuilt, put everything back together, and cruise is working fine.

But with the 92, not only was the amp fried by the actuator, but it was SO bad that the amp was not even re-buildable! You should see the blackened circuit board!

All of which is to say this: yes, I’m sure many times all that’s needed to get cruise up and running again is somehow to address the amp. But there are those cases when the amp is bad because it has been damaged by the actuator. Simply fixing the amp is a waste of money. So I guess what I’ve learned is never to leave the actuator out of the equation in a diagnosis.

I suppose I’m fine having only one car with cruise. But, on the outside chance that anyone has a parts car with a functioning amp and actuator, I might be interested. Actuator part no. is 0025458632; amp part no. is 0055450532.

Finally, I should say that I remain really impressed with GDL. Peter really seems to know what he’s doing and is a pleasure to do business with. It’s certainly not the least expensive route to go, but I’m glad to have some peace of mind that I’ll have cruise for many years to come.


PS While I toyed with the idea of going the aftermarket route with Audiovox, Rostro, etc., I chose not to because I just didn't have the confidence I could do my own work. For those with greater expertise, this may be the more cost-effective choice. Yet, I must admit, there is something nice about original equipment.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Yup, I went through this a few years ago; I ended up buying a rebuilt amp and a new actuator from GDL. The system has worked perfectly ever since, replacing everything together is the least aggravating solution.